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Fish

This document provides information about the history and anatomy of fish. It discusses: - The earliest fish, ostracoderms, from 425 million years ago that lacked jaws. - Two groups of jawed fish that evolved around 395 million years ago: placoderms with fused upper jaws and acanthodians with bony spines. - The general characteristics of modern fish, including being cold-blooded, breathing with gills, and moving with fins to maintain salt and water levels. - The external anatomy of fish including fins, scales, eyes, mouth and lateral line sensory system. - The internal organs of fish such as gills, heart, liver, kidneys and swim bladder that aid

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HISTORY  Ordovarian Period (425-500 million years ago)  OSTRACODERMS ○ Slow, bottom-dwelling animals ○ Covered with thick bony plates and scales ○ Had very poorly developed fins and didn’t have jaws ○ Believed to be the first animal with backbone  Extinct about 250 million years ago
2 Groups of Fishes with movable jaws PLACODERMS ACANTHODIANS  Appeared about 395 million years ago  Had thick, bony plates and paired fins  Their upper jaw was fused to the skull while the lower jaw was hinged and movable  Extinct about 345 million years ago  Class Chondrichthyes evolved  Appeared about 410 million years ago  Distinguished by the bony spines projecting in front their fins and by minute diamond-shaped scales  Class Osteichthyes evolved
GENERAL CHARACTERICTICS  Fish are cold-blooded vertebrates that breathe with gills and move with the aid of fins.  They have the most numerous vertebrates with more than 30, 000 species.  All fish must maintain proper levels of salt and water in their bodies through osmosis.  Freshwater fishes: Body salts are higher in concentration than surrounding water  Saltwater fishes: Surrounding water has higher concentration than their bodies
 Most fish are able to react to changes in water pressure, temperature, currents and sounds.  Fish have taste buds in their mouth, on their lips and on their body and fins. Some are on their barbels (whisker-like projections around their mouth)  Has highly developed sense of smell
Philippine island goby (Pandaka pygmea) The smallest fish. Only 1/3 or ½ inch long.
Whale Shark (Rhincodon typus) The largest fish. Average size is 25 feet long. Grows about 50 feet and weigh up to 15 tons.
EXTERNAL ANATOMY EYE MOUTH OPERCULUM (GILL COVER) PECTORAL FIN ANAL FIN PELVIC FIN LATERAL LINE SOFT DORSAL FIN CAUDAL/TAIL FIN SPINY DORSAL FIN SCALES VENT NOSTRILS PENDUCLE
Scales  Thin bony plates that overlap each other and provide protection.  Develop from and are embedded in a pocket of the dermis.  The exposed part is covered with a thin layer of epidermis. Four types of scales: 1. Ctenoid 2. Cycloid 3. Gamoid 4. Placoid
1. Ctenoid ○ Have serrations on the edges and rough surfaces 2. Cycloid ○ Have smooth surfaces and edges that make the fish feel smooth and slick 3. Ganoid 4. Placoid
Skin  it contains glands that produce a slimy mucus which makes the fish slippery and provide protection from bacteria  Contains chromatophores which are pigment cells that give the fish its colors. ○ Usually allows to blend with its surroundings  Sensory receptors are also contained in the skin
Anal fin  Single  Found on the underside near the tail  Acts as rudder or keel to help steer the fish during faster motion  In some species, this has adapted to become a sex organ
Fins  Movable structures that aid the fish in swimming and maintaining its balance.  Most have rayed fins.  These fins consist of a web of skin supported by a bone or cartilage rods called rays ○ May have sharp, spiny or soft rays  Very flexible
 Pectoral fin  generally in symmetrical pairs  Found on the side just behind the head  Used to stabilize, rotate and stop the fish during slower motion
Caudal fin  Single; also called tail fin  Together with the caudal penducle, they generate the forward thrust in most fish. These are the main release point for that forward thrust.
Pelvic fin  also called ventral fins  Generally in symmetrical pairs  Found below and just behind the pectoral fins  Used in similar fashion to the pectoral fins
Dorsal fin  Found along their back  Soft dorsal fin ○ Used to stabilize the fish and keep them upright ○ Has similar purpose to the anal fin.  Spinous dorsal fin ○ Also used to stabilize and keep them upright ○ Spiny and sharp ○ In some species, it contains venom for protection from predators. ○ Display of an erect dorsal fin shows readiness to mate and is in prime condition therefore a good mate
Eyes  Has spherical lens that focuses by moving within the eyeball, not by changing the curvature of the lens  They don’t have eyelids, kept moist by the water  Size usually depends on the amount of light reaching the eye ○ Fish living shallow and brightly lit waters have small eyes ○ Those that live in dimly lit water have big eyes
Lateral line  Series of fluid-filled ducts/sacs with hair-like sensory apparatus that are open to the water through a series of pores located just under the scales.  Neuromasts – Row of sensors that allow the fish to detect movement (vibration) around them in order to capture prey, elude predators and navigate efficiently
Mouth  Have taste buds  Feeding/food is based on its shape ○ Top dwellers – upturned ○ Middle dwellers – small mouths and are straight forward, neither upward nor downward ○ Bottom-dwellers – downward turned or underslung
Nostrils  Used to detect odors in water and can be quite sensitive
Operculum (Gill cover)  Flexible bony plate  Protects the sensitive gills
Vent  External opening to digestive urinary and reproductive tracts
INTERNAL ANATOMY BRAIN GILL HEART LIVER STOMACH INTESTINES PYLORIC CAECA GONADS (EGGS) MUSCLES KIDNEY SWIM BLADDER SPINAL AND SPINAL CORD
Kidney  Filters liquid waste materials from the blood then these waters are then passed out of the body  Regulates water and salt concentrations within the fish’s body allowing certain fish species to exist in freshwater or saltwater and in some cases both
Liver  Assists in digestion by secreting enzymes that break down fats  Serve as storage area for fats and carbohydrates  Destroys old blood cells  Maintains proper blood chemistry  Plays a role in nitrogen (waste) excretion
Muscle  Provides movement and locomotion  Part usually eaten and composes the fillet or fish
Spinal Cord  Connects the brain to the rest of the body  Relays sensory information from the rest of the body to the brain and vice versa Spine  Primary structural framework upon which the fish’s body is built  Connects to the skull at the front and to the tail at the rear of the fish.  Made up of numerous vertebrae (hollow which house and protect the delicate spinal cord)
Stomach and Intestines  Break down (digest) food and absorb nutrients  Piscivorous fish (eat other fish) have fairly short intestine because such food is easy to chemically break down and digest  Herbivorous fish (eat plants) require longer intestines because plant matter is usually tough and fibrous and more difficult to break down into usable components
Swim Bladder  located in the abdominal cavity  Filled with gases produced by blood which enables the fish to maintain a particular depth.  A few bony fishes are able to breathe atmospheric air because their swim bladder is supplied with blood vessels thus allows it to function like a lung  A few fish species have a part of their intestines that are modified to allow oxygen intake. ○ They rise to the surface and gulp air into their mouths ○ The air is swallowed into the digestive system, then taken to the blood.
 Anabantoid fish have special rosette-shaped plates in a labyrinthine chamber behind their gills ○ These are supplied with numerous blood vessels that absorb oxygen from the atmospheric air they inhale through their mouth >>These are important adaptation for fish living in swamps or other waters that are poorly oxygenated
AQUARIUM  The term combines the Latin root aqua, meaning water, with the suffix -arium, meaning "a place for relating to“
TYPES OF AQUARIUM  Community Aquarium  Freshwater and Saltwater Aquarium  Mix of fish and plants originating from different geographical areas with emphasis placed on color and hardiness  Can be successful if it follows the basic rules for compatibility of its inhabitants with respect to temperature, water chemistry, aquarium size and character  Planted aquariums  Features emphasis on plants and limited fish populations  Typical fish species are tetras or rasboras and some angelfish  Lighting and attention to appropriate filtration media are important details
FILTER FILTER SYSTEMS FILTER MEDIA HEATER AIR PUMP THERMOMETER LIGHTING AQUARIUM DECORATIONS TEST KITS
FILTER  Remove solid waste and uneaten food materials from the water  For water purity and quality  Takes out visible particles, breaks down toxic substances, and removes harmful chemicals in aquariums
Filter Media  Is the content of a filter system which is in contact with the water flow and is the substance that actually performs the mechanical, biological and chemical filtering.
MECHANICAL FILTRATION  Removal of particulate waste from the water  Mechanical filter media, which is very fine, will trap greater quantities of debris and plug more rapidly Regularly remove accumulated debris. This will help support superior oxygen levels, stable water conditions and reduce nitrate accumulations.
 Foam  is an excellent mechanical filter media.  The porous channel structure within the foam obliges the incoming water to deviate from a straight path, maximizing contact time and giving the foam a huge holding capacity for debris.  Maximum mechanical effect is achieved after approximately 10 to 14 days.  It also supports essential bacteria and can be a mechanical and biological filter media, as evidenced by internal filter systems, as long as a regular water change schedule is respected.  Polywool  Effective mechanical filter media that will remove fine particles and prevent other filter media from being prematurely clogged.  It will contribute to polishing aquarium water for ultra clear conditions.
CHEMICAL FILTRATION  Active control and change of specific water characteristics.  Filter media and various products exist that clarify water, eliminate odor, remove chlorine, eliminate medications after disease treatments, neutralize heavy metal ions and effect changes in hardness and pH levels.  Specific chemical filter media should be used to optimize water conditions for various groups of fish and plants. This will ensure that fish and plants will look their best and stay healthy.
 Accomplished with the use of activated charcoal (soaks up dissolved minerals and chemicals)  Activated charcoal can be placed in box filters or return water can flow through the charcoal. Charcoal must be replaced periodically as it reaches the point where it can no longer absorb dissolved materials.
 Carbon  highly adsorptive and is capable of removing odors and liquid wastes such as urine, dyes and many other impurities from aquarium water.  Provides the correct pore size and selection of optimal raw ingredients to provide long lasting aquarium filtration. This is very important as there are carbons that are manufactured using raw materials which are designed for filtering air, not water, and are sold for aquarium use.  Opti–Carb  An advanced chemical filter media that combines a high quality carbon with both a synthetic Organic Adsorption and Ion Exchange Resin.  This potent combination of ingredients will ensure that aquarium water is effectively free of dissolved protein matter, toxic heavy metals, dissolved gasses that cause odor and discoloration for a crystal clear aquarium.  Both fresh and saltwater aquariums will benefit from improved water quality. Fresh and saltwater fish will thrive in ultra pure water while plants and corals will benefit from improved light availability due to ultra clear water conditions.
 Phosphate Remover  Phosphate is major nutrient and is undesirable within freshwater aquariums that do not contain plants and in marine aquariums in general. It’s presence is linked to undesirable aquarium conditions and can result in an unsightly appearance.  Pre-Filter  consists of inert, solid rings that are ideal for medium to coarse filtration. These durable rings also serve as a surface for beneficial bacteria, contributing to biological filtration.  Ammonia Remover  natural mineral, which safely and effectively scavenges ammonium from aquarium water.  Particularly useful when chloramine is present in tap water, and in instances where ammonia can occur, such as new aquariums, fish loss, overfeeding, after disease treatment, and overpopulated installations.
 Zeo-Carb  Combines Ultra Grade Carbon and Ammonia Remover to protect the aquarium from build-ups of ammonia and liquefied waste, dyes and medication.  It effectively controls and removes ammonia while trapping organic compounds. In addition, it also supports biological filtration.  Nitrate Remover  Effectively bind large quantities of Nitrate and highly toxic Nitrite.  As ammonia and nitrite are continuously converted by nitrifying bacteria, there is an accumulation of nitrate. The greater the concentration of fish and other life within the aquarium the faster Nitrate will accumulate. This is a direct reflection of poor water quality as well as being a major factor in unsightly aquarium conditions. Regular use of this product is highly recommended for well stocked freshwater aquariums, especially those that do not contain live plants.
BIOLOGICAL FILTRATION  Neutralize toxic substances, essentially ammonia excreted from fish during respiration and produced from decaying waste and food materials.  In this system, a slotted plastic plate is placed in the bottom of the aquarium.  A 2 or 3 inch layer of gravel is placed over the slotted plate; should be 0.125 inches in diameter  Gravel containing large particles allows food to fall and decay while too small particles block the air pump
 Aquarium Peat  Highly desirable filter media which is very beneficial for aquariums containing plants, South American Cichlids, Tetras, Gouramis, Rasboras, Killifish, and many other species of fish originating from acidic waters.  Peat will lightly stain the water a natural tan color, lower pH and KH values, and release natural substances, optimizing aquarium water conditions for many fresh water fish and aquatic plants.  Fish that originate in acidic water will exhibit optimum coloration, improved behavior and reproduction.  Peat can also have a positive effect in supporting acidic water conditions  Bio-Max  Perfect biological media for fresh or salt water aquariums.  BioMax porous cylinders are capable of supporting huge populations of water purifying bacteria. They are composed of 85% Micro-Tunnels, ideal for hosting the beneficial bacteria which consume toxic ammonia and nitrite. The remaining 15% are micro-cavities, ideal for hosting other species of beneficial bacteria that can contribute to biological filtration.
Air pump  Achieves aeration (air or gas passing through)  Pumps are either:  Vibrator-diaphragm type  Rotary-vane type
Waste and ammonia  Fish excrete waste and an unestablished (or uncycled) aquarium is not capable of processing these waste materials efficiently, so this creates toxic conditions for the fish. The result is fish loss. Your aquarium water must be free of toxic compounds in order for fish to survive and thrive.  Ammonia, perhaps the most notorious toxin, is introduced into your aquarium through fish waste, respiration, and other biological processes. It is extremely toxic and fish will show signs of stress, such as erratic swimming behavior, when ammonia is present. High levels of ammonia attack the gills first, causing fish to gasp at the surface. Continued exposure affects their fins and skin, and eventually their entire system is under attack.
 Factors contributing to the increase of ammonia and nitrites:  Increase in waste material and uneaten food on the bottom of the aquarium  Dirty filters  Failure to change water at regular intervals ( ¼ to 1/5 of the water should be changed every 3 to 4 weeks)  Overfeeding  Overpopulation of fish
 In an established aquarium, ammonia is promptly converted into less toxic substances by beneficial bacteria through a natural process called the nitrogen cycle.  New aquariums do not have established colonies of beneficial bacteria to adequately process these toxins.
Cycling  The process of establishing and maturing biological filtration.  The nitrogen cycling process that all new aquarium setups go through when they first start is what leads to the birth of the aquarium's biological filtration. From start to finish, this cycle usually takes around 30 to 45 days to complete.  Importance:  In order to establish efficient biological filtration capable of breaking down these toxic compounds.
 Nitrification  Growth of colonies of aerobic bacteria  Most efficient at a pH of 9  Nitrosomonas ○ Coverts ammonia into nitrites  Nitrobacter ○ Converts nitrites into nitrates pH scales read: 0 = very acidic 14 = very alkaline 7.0 = neutral
The Nitrogen Cycle
Importance  The nitrogen cycle of an aquarium is a natural chain of events resulting in the colonization of various types of nitrifying bacteria, each with their own job to do. Without a strong, healthy biological filter, an aquarium will never be able to support a healthy population of fish and invertebrates.
 What does toxic ammonia convert into during the nitrogen cycle?  First, oxygen-loving bacteria, called Nitrosomonas, feed on ammonia and through biological processes they excrete nitrite, a less toxic but still dangerous chemical.  Another oxygen-utilizing bacteria, called Nitrobacter, feeds on the nitrite, converting it into relatively harmless nitrate. Nitrate can be used by plants in the aquarium, or can be removed with water changes.
HEATERS  Warms water to maintain water temperatures preferred by tropical fish  Stabilizes the water temperature for the health of the fish  There are two types of heaters:  Submersible  Electronic
THERMOMETER  To monitor water temperature and heater accuracy
LIGHTING  Brings out extraordinary colors in the aquarium and facilitates the growth of live plants  For viewing aquarium inhabitants or for healthy live plants
TYPES OF LIGHTING  Fluorescent  Incandescent  LED
Factors that influence the type and quantity of light required:  Size of aquarium  Fish species and other aquatic inhabitants  Plant life  Aesthetics
Lighting tips:  Most plants require approximately 12 hours per day of light from a fluorescent fixture.  Sudden changes in light may stress fish. When turning canopy lights on or off, it is beneficial to have room lights on for at least 30 minutes.  Fish fed during the day should be allowed 30 minutes of light before and after feeding.  Use timers when possible. Plants and fish will respond better to consistent lighting periods.  Plants and fish will adapt to gradual light changes. When changing bulbs in a multiple bulb installation, change 1 to 2 weeks apart.
 A remote ballast should be mounted in an area where there is adequate ventilation to efficiently dissipate heat. This is especially important in ballast types that generate more heat.  Electrical wiring leading to the ballast should always incorporate a drip loop.  Consider a GFI (Ground Fault Interrupter) power bar as an inexpensive insurance to avoid unpleasant circumstances surrounding any potential electrical mishaps.  Do not leave lights on 24 hours a day. As in nature, fish and plants require dark periods as well.
 To make it attractive  Also provide shelter and hiding places for inhabitants  Plants can be added for attractiveness and to provide a means of using carbon dioxide while releasing oxygen AQUARIUM DECOR
AQUARIUM DECOR  GRAVEL
 DRIFTWOOD
 SHELLS
 ORNAMENTS
 ARTIFICIAL PLANTS
 AQUARIUM BACKGROUNDS
 CORRALS  ROCKS
Water star Water milfoil Live plants
Amazon sword plant Arrowhead
Ambulia Giant eel grass
Willow moss Ludwigia
Java moss Java fern
Japanese dwarf rush Indian water star
Hornwart Hairgrass
 TEST KITS
Success Begins with Research 1. What aquarium inhabitants are appealing to you and what others can be housed with them? 2. What size and shape of aquarium is recommended for them? 3. What types of filtration, lighting, decorative structure, and accessory equipment are needed in order for the aquarium inhabitants to thrive? 4. What feeding and maintenance is required to keep them healthy? 5. Most importantly, are you willing to invest the time and money necessary for ongoing maintenance?
Rules of the thumb  Generally, the larger the aquarium the better, unless it will be too heavy for the flooring to hold it. A tank that is filled with gravel and water will weigh at least 10 lbs. per gallon. That adds up quickly, if you consider that a seemingly small 20-gallon tank will weigh 200 pounds . . . and that does not account for the stand, lighting, or filtration!  It is imperative to choose a sturdy stand to hold the tank. If you choose to setup your tank in an environment frequented by small children, choose a stand that cannot be climbed on or pulled over.  Choose a filter appropriate to the type of inhabitants you are keeping and water capacity of the tank. Buy the best filter that you can afford. At minimum, a filter should provide mechanical and biological filtration.  Next, you'll need a heater and a good thermometer. Make sure the heater is at least 3-5 watts per gallon. For example, a 50-gallon tank would require a 150-250 watt heater.
 You will need to choose an aquarium cover or hood. If the inhabitants require special lighting, you'll want to purchase a fixture that can accommodate it.  A water conditioner will be needed to remove chlorine and heavy metals if they are present in your water supply.  Don't forget a net!  Now, you're ready to decorate. It's essential to choose decorations that provide fish with structure and hiding places to relieve stress. Plants and decorations can also be used to conceal filter parts. Gravel in the bottom of the tank holds plants and decorations while hiding wastes. If you will be using an under gravel filter, the gravel should be about 2 inches thick. Dark colors will make the fish color appear more vibrant.  A gravel cleaner and algae cleaner will be needed within 30 days so you can begin regular maintenance.  Before you place the items in the tank, rinse them off and rinse gravel thoroughly until water drained off is clear.
 Choose a sturdy, level area to set up the tank.  Set up the stand, then the tank. Pour in cleaned gravel.  Fill the tank with tap water about 3/4 full, then put in decorations, set up filtration, heater, and thermometer. Continue filling aquarium to 1/2" from bottom of rim. This allows extra space for when you put your first batch of fish in to acclimate.  Now, you're ready to start up filtration, heater, and add any water conditioners needed. Assemble lighting/cover. Then, wait until tank heater has adjusted the water to the correct temperature (75°F for most fish) and maintains it.  Finally, you can purchase your fish and acclimate them to their new home; remember not to put too many in at one time.
10 BASIC TIPS FOR A SUCCESSFUL AQUARIUM 1. AVOID OVERCOMPENSATING Instead: Assess the situation and determine a prudent course of action. Many situations benefit from patience rather than misguided action. 2. AVOID ADDING TOO MANY FISH TOO SOON Instead: Allow two to three weeks between each introduction of new fish. Also, use a biological additive with every addition. Adding too many fish too quickly taxes the biological filter. The subsequent spike in ammonia level can often result in fish loss. 3. AVOID SKIPPING QUARANTINE Instead: Always house new fish in a separate quarantine aquarium for a minimum of 2 weeks for observation and treatment of potential illness. 4. AVOID NEGLECTING WATER TESTS Instead: Test aquarium water regularly to make sure water parameters are within acceptable levels. Many common aquarium pollutants are invisible. Regular water testing is the only accurate way to detect toxins such as ammonia or nitrite. 5. AVOID OVER-CLEANING Instead: Stagger water changes and perform partial gravel cleaning to preserve vital beneficial bacteria. Aggressive cleaning can upset established biological filtration by removing beneficial bacteria. An imbalance may result where ammonia levels exceed the processing capacity of the diminished bacterial population.
6. AVOID UNDER-CLEANING Instead: Perform routine partial water changes and follow the manufacturer's recommended schedule for replacing filter media. Lax maintenance habits have a cumulative negative effect on overall water quality. Not only do pollutants accumulate to unhealthy levels, it becomes more difficult to bring aquarium conditions within acceptable parameters. 7. AVOID SKIPPING RESEARCH Instead: Research care requirements of the species you are interested in first. Resist impulse purchases. Make sure you are able to properly provide for the species and that your aquarium is capable of supporting the new addition. Also, confirm compatibility of existing aquarium inhabitants. 8. AVOID "GENERIC" EQUIPMENT SELECTION Instead: Purchase equipment that satisfies the specific needs of YOUR aquarium inhabitants. Each aquarium setup is unique, so research and customize filtration, lighting, water movement, and aeration requirements. 9. AVOID IMPROPER NUTRITION Instead: Offer a wide variety of foods, including flake foods, freeze-dried foods, and frozen foods. Avoid over-feeding by following the manufacturer's feeding instructions. Adjust feeding amount so fish are able to finish the dispensed portion within a couple minutes. 10. AVOID IMPROPER USE OF BOTTLE REMEDIES Instead: Always read and follow the manufacturer's label completely before dispensing any medications, water conditioners, or algaecides. More does not always mean better results.
Fish pond  a controlled pond, artificial lake, or reservoir that is stocked with fish and is used in aquaculture for fish farming, or is used for recreational fishing or for ornamental purposes.
STEP-BY STEP 1. MAKING CONTOURS 2. THE DIGGING 3. THE LINER • 1st layer – polyester • 2nd layer – rubber 4. INSTALLING EQUIPMENT  Filter system 5. ADDING STRUCTURE
THINGS TO CONSIDER: 1. LOCATION  A place with a good mixture of sun and shade.  Build on a natural hill so we could put a waterfall using a terrain. 2. STYLE/SIZE  Depth  Levels  Most comfortable way of enjoying and feeding the fish 3. MAINTENANCE COMMITMENT 4. SELECTING FISH 5. PLANT 6. WATERFALL
Water hardness  Hardness – caused by a dissolved magnesium and calcium salts  can be diluted by removing some of the hard water and adding soft water  2 types:  Temporary ○ can be removed by boiling the water  Permanent ○ Removed by chemical means or distillation
 Measured by:  German scale measure (°DH)  Clark or English scale measure (°H)  ppm (parts per million of either CaCo3 or CaO)  gpg (grains per gallon) Conversion factors: 1 °DH = 17.9 ppm CaCo3 1 °H = 14.3 ppm CaO
Selecting Healthy Fish  Clear Eyes (not cloudy).  Erect, undamaged fins.  Scales should be intact, parallel with body (not sticking outwards) and no red blotches.  No holes, ulcerations, or lumps.  Species with translucent bodies, no inner appearing whitish areas.  Active, lively, normal swimming patterns (some species are naturally shy and reclusive).  No white spots (salt grain size) or white cottony growths on the fins or body.  Respiration rate should be regular and steady (in unstressed circumstances).  Gills should be red inside, not faded or discolored, and not distended or puffy.  Actively feeding.  Avoid selecting fish from a system that contains any sick specimens.
ACCLIMATION OF NEW FISH  Close the aquarium lights during the acclimation period. Float the bag in the aquarium for approximately 20 minutes to equalize water temperatures.  Open the bag and gently pour in some aquarium water (approximately 1/3 the bag volume), wait 10 minutes. Repeat this water introduction twice more at the same interval.  Carefully net the fish out of the bag and place them in the aquarium. Dispose of the water in the bag, DO NOT release this water into the aquarium.  If the newly introduced specimens are the only ones in the aquarium, wait 24 hours before initial feeding.
To determine the number of fish can be put in a tank  One should multiply the length by the width to determine the square inches of surface area  Rule of thumb:  Tropical Freshwater aquarium – no more than 1 inch of fish for every 10 square inches of surface area  Cold Freshwater aquarium – 1 inch of fish for every 30 square inches of surface area  Marine aquarium – 1 inch of fish for every 48 square inches
SUBORDER CHARACOIDEI FAMILY CHARACIDAE FAMILY GASTEROPELECIDAE FAMILY ANOSTOMIDAE FAMILY HEMIODONTIDAE SUBORDER CYPRINOIDEI FAMILY CYPRINIDAE FAMILY GYRINOCHEILDAE FAMILY COBITIDAE
Family Characidei  Large family containing 1,300 species: about 1,000 are found in Central America and the remaining are found in Africa  Most are brightly colored and have narrow dorsal fin and small adipose fin.  Most are omnivorous and consume all types of food while few are carnivorous  Inhabit shallow, slow-moving rivers of the rainforest and live among sand and ground shoal areas.  Most are sociable and do well in the aquarium community
TETRA Blind Cave Fish Astyanax mexicanus  Native to the underground caves of Mexico  Grows about 3 ½ inch long  Primarily flesh colored and fins are colorless  The young has eyes but as they mature skin grows on them thus nonfunctional  Uses their sense of smell to seek out and consume food
Bucktoothed Tetra Exodon paradoxus  Grows about 5 ½ inch in lenth  Very aggressive and should be kept in thickly planted aquariums with fish that are able to protect themselves  Gold-colored with reddish orange fins  Feed on vegetation and fruit  Native to South America
Red-eyed or Glass Tetra Moenkhausia oligolepis  Grows slightly less than 5 inches in length  Silver gray with dark edges to the scales on the upper body  Upper part of the eyes is red  There is a yellow band around the penducle and a black band at the base of the caudal fin
PIRANHA Red Piranha Serrasalmus nattereri  Most widespread among the piranha species  Found in South America  Grows about 12 inches in length  Disc-shaped, muscular and very powerful  Eats young fish, lean meat, meat-based flake foods and insects  Primary color is steel gray, darker blue-gray color back and red underside with numerous black spots  Must be kept in an aquarium by themselves  Temperature should be maintained at about 78 F