This document discusses the feeding habits and nutritional requirements of fish at different life stages. It begins by explaining that fish require energy, amino acids, fatty acids, vitamins, and minerals to sustain life and promote growth. It then discusses the feeding behaviors and nutritional needs of fish larvae, including their underdeveloped digestive systems and reliance on plankton and zooplankton. The document also categorizes different types of food sources for fish and classifies fish based on their dependence on food types and positions in the water column. Specific examples are provided of the feeding behaviors of fish larvae, juveniles, and adults.

1. Presented by
Satyaveer
Department of Fisheries Resources & Management
College of Fisheries Mangalore

2. INTRODUCTION
• Fish must have an energy source to run the body machinery. They also require an
adequate amount of essential amino and fatty acids plus vitamins and minerals to
sustain life and promote growth.
• Nutrient requirement of all animals vary throughout their lifecycle
(Morphology, Physiology of larvae, fingerlings and adult stage)
• Larval – Active swimming and actively feeding
• Nutrition requirement of larvae
Morphology
Digestive process
Feeding behavior

3. • Larvae feed actively before their digestive system is well developed
• At larval stage fishes are more choosey
• First feeding is done by live feed either planktons or zooplanktons
• Growth will be rapid
• Larval mouth size decides the feed particle size
• In wild larvae feed mainly on planktons-depends on coloure, shape, size and
nutritive valve of the plankton or zooplankton
Conti…..

4. Categories of food
Plankton : Plankton is microscopic organisms with little or no power of
locomotion. They drift at the mercy of water currents.
• Phytoplankton – having chlorophyll in the cells e.g. Diatoms, Dinoflagellates
• Zooplankton – without chlorophyll e.g. Copepods, crustacean larvae, other
microscopic invertebrates
Nekton : Nekton are actively swimming organisms capable of independent
movement. They may be present at the surface (pelagic) or at the bottom
(demersal) of water column. e.g. fishes, shrimps, cuttlefishes and squids.

5. Conti…..
Benthos : These are bottom dwellers with little (sessile) or no movement
(sedentary). They are mostly invertebrates living on the substratum. e.g. annelid
worms, bivalves, gastropods etc., benthos are of two types
i) phytobenthos and ii) zoobenthos.
Detritus : It is the dead and decayed organic matter of both plant and animal
origin. Decomposing bits of leaves, twigs, barks, water plants and animals form
detritus. It can be in particulate or suspended form associated with rich microbial
flora and fecal matter.

6. Classification of food based on its
Importance
Occasional or secondary food : When the main food is not available, fish
feed on other available food temporarily.
Incidental food: This type of food that occasionally enters the gut of a fish
along with main food items.
Emergency or obligatory food : This is the one which fish takes in the
absence of basic food to maintain physiological activities. It is taken when
there is no alternative food available.

7. Fishes are categorized based on their dependence on food type, preference,
position in water column and feeding types.
Dependence on food type : In nature, the type of food available does not
remain the same throughout. Therefore, fish may change over to other available
food or restrict to a limited type and the fishes are classified as:
• Euryphagic : Fishes feeding on a mixed diet with no preference to any certain
type.
• Stenophagic : Fishes feeding on limited kinds of food.
• Monophagic : Fishes consuming only one kind of food.
Conti…..

8. • Herbivorous :A number of fishes feed on unicellular algae, filamentous algae,
and also higher aquatic plants.
If the plant material in the diet is 75% or more the fishes are considered to be
herbivorous. i.e. Labeo fimbriatus, L. rohita, Ctenopharyngodon idella.
• Detritivorous : Those feeding mainly on detritus i.e. Labeo calbasu, Mugil
cephalus.
Conti…..
Omnivorous : Those feeding on both plant and animal matter. The food of these
fishes consists of varying percentage of plant and animal matter and they form a
link between herbivorous and carnivorous fishes. i.e. Etroplus suratensis,
Cyprinus carpio, Tor putitora, Cirrhinus mrigala, Clarias batrachus,
Heteropneustes fossilis.

9. • Planktivorous : Feeding mainly on plankton both phyto and
zooplankton i.e. catla - zooplankton feeder , silver carp - phytoplankton feeder.
• Carnivorous : Feeding on prey organisms. The examples of carnivorous
fishes are: Wallago attu, Mystus singhala, Channa striatus.
Conti…..

10. • Insectivorous: Mainly feeding on insects. i.e. Trout.
• Carcinovorous: Mainly feeding on crustaceans. i.e. Black bass
• Malacovorous: Feeding mainly on molluscs like snails/clams i.e. Black carp
• Piscivorous: Feed on fish other than its own species. But, generally they prey
upon small fishes of other species rather than their own i.e. Barracuda.
• Larvivorous: Feeding mainly on insect and crustacean larvae/fish
larvae. i.e. Gambusia affinis.
• Cannibalistic: Feeding on the young ones of the same species i.e. Channa
marulius, Lates calcarifer.
Conti…..

12. Yolk
• May be protein, fat
• Yolk granules smaller at the periphery towards center
• Unite and forming a homogenous mass

13. Eggs with Amount of yolk
• Microlecithal eggs: are small with little yolk Eg: Bivalves
• Mesolecithal eggs have relatively more yolk than the microlecithal eggs Eg:
Lampreys
• Macrolecithal eggs :have a large yolk Eg: Cephalopods

15. LARVA AND JUVENILE IN FISHES
(as per the feeding habit)
1. Yolk-sac larva or Pro larva - which retains the yolk.
• Yolk-sac larva – mostly develop in external environment , with or without
parental care – yolk sac usually elongated and homogenious.
3. Post-larva - pre-adult stage, resembles adult .
• Post-larva—herbivorous or carnivorous / mouth may be superior ,inferior,
terminal, digestive system well developed / resembles the adult
2. Pre-larva - yolk-sac absorption stage to juvenile stage.
• Pre larve- starts feeding on external food like phyto or zoo plankton, mouth wil be well
developed , gut wil be long in case of herbivorous n short in case of carnivorous

16. Weaning period !

17. Morphology
Mouth size
Food particles
• Large – Starvation is inevitable
• i.e, Murray cod – Large mouth, Artemia nauplii
• Small – Poor growth
• i.e, Flounders – Small mouth, ciliate protozoans/mollusc villigers

18. Digestive Process
• Increasing morphology complexity leads to development of digestive process
• Epithelial cells of digestive tract are absorptive in swim up larvae – secretion
of digestive enzymes are limited
• Digestive enzymes (Protein degrading) – Trypsin, Chymotrypsin,
Carboxypeptidase and Pepsin

19. Larval groups According to alimentary tract, and
morphology of the gut and enzyme secreted
• Salmonids & catfish - Functional stomach before changing from endogenous
to external feed
• Striped bass & marine species - Rudimentary digestive system
• Develop a functional digestive tract but remain stomach less throughout life
e.g.. carps

20. Nutritional requirements
• For growth and development 40 essential dietary requirements are required
by fish
• The important nutrients are:-
Proteins
Lipids
Carbohydrates
Vitamins
Minerals

21. Larval stages of carps
Generally carp seed is classified into 3 categories
• Spawn (hatchlings up to 8mm)
• Fry (8mm to 40mm)
Early fry(8mm-25mm)
Advance fry(25mm-40mm)
• Fingerlings(40mm to 150mm)
Advanced fingerling(80mm_150mm)
Early fingerling (40mm-80mm)

22. Feeding practices
• Feeding schedule followed in carps:
• Spawn to fry: 4 times of initial body weight during first week and 8 times
during second week
• Fry to fingerling:6-8% of biomass first month
5-6% during second month
3-4% during third month

23. Feeding behaviour affected by
• Environment
• Time of the day
• Tidal amplitude
• Season

24. Important live food organisms

25. • Unicellular organisms:
• Yeast
• Algae
• Live animal prey:
• Copepod
• Rotifer
• Artemia

26. Common Rotifers

27. Common Rotifers

28. Common
Cladocerans

29. Copepods

30. Ostracods

31. In general food and feeding habits of Indian
Major Carps
Stages Food
Larvae Planktonic
unicellular algae
Fry Zooplankton
organisms
Catla
Mrigal
Rohu

32. Fish food preferences

33. 1.Herbivorous
• Fishes feed on unicellular algae, filamentous algae, and also higher aquatic plants.
• If the plant material in the diet is 75% or more, the fishes are considered to be
herbivorous
Eg: Labeo fimbriatus, L. rohita, Ctenopharyngodon idella, Oreochromis
mossambicus .

34. Tilapia
Stages Food
Larvae Phytoplankton
Fry & fingerling Benthic algae 75% &
periphyton

35. 2. Planktivorous :
• Feeding mainly on plankton both phyto and zooplankton
• Catla - zooplankton feeder
• Silver carp - phytoplankton feeder

36. Indian Oil Sardine
Stages Food
Larvae Phytoplankton, planktonic
crustaceans like copepods
Juvenile &
adult
Diatoms (80%) like Fragillaria
oceanica, Coscinodiscus,

37. 3. Detritivorous :
• Those feeding mainly on detritus
• Eg: Labeo calbasu,
Mugil cephalus.

38. Mullets
(Mugil cephalus)
Stages Food
Larvae Planktonic unicellular algae (95%)
Fry feed on zooplankton until about 3.0
cm
Mullets are diurnal feeder
They are having gizzard stomach
• Also graze on epiphytes and epifauna from seagrass and surface scum

39. 4.Omnivorous
• Feeding on both plant and animal matter.
• Varying percentage of plant and animal matter and they form a link between
herbivorous and carnivorous fishes.
• Cyprinus carpio,
• Tor putitora,
• Cirrhinus mrigala,
• Clarias batrachus,
• Puffer fish are omnivorous animals and eat a variety and plants and animals.
Puffer fish mainly feed on the algae that grows on the rocks and coral and
also ...

40. Anchovies
Stages Food
Larvae Phytoplankton : diatoms (40%),
dinoflagellates(30%) and
zooplankton

41. Pearl Spot
Stages Food
Larvae Zooplankton
Advanced fry Aquatic insects larvae, filamentous
algae and other vegetable matter.

42. 5. Carnivorous :
• Feeding on prey organisms.
• Wallago attu,
• Channa striatus.

43. Milk fish
Stages Food
Larvae lab lab
Fry Copepod and diatoms
After 5 days of hatching the
larvae starts to feed

44. Sea bass and Sea breams
• Sea breem: Found in shallow temperate and tropical waters
• Bottom-dwelling carnivores.
• Most abundant in
Tropical Atlantic, Indian & Western Pacific oceans
• Some species are found in the Eastern Pacific.
Eggs measure about 0.9-1.1mm.
• Larve:Start feeding from 3rd to 4th day after hatching (larvae 2.5-3mm )

45. Stage Food
Larvae Chlorella sp., Tetraselmis sp.
Fry Artimea and copepods
Fingerling Rotifers
Lates calcarifer
Sea breams

46. Groupers
Stages Food
Larvae Zooplankton
Fry and fingerling Mysids & small
shrimps

47. Elasmobranches
• Carnivores and predaceous in
nature
Stages Food
Larvae Zooplankton,
Fry and
fingerling
larvae of prawns, squids and
anchovies. larva of some other fishes
and crustaceans
Adult Sharks mainly feed on pelagic
teleost's such as sardine, mackerel,
Bombay duck etc. and cephalopods
(squid, octopus, and cuttlefish)
Skates and rays mostly feed on
benthic organisms viz. crustaceans,
molluscs, polychaetes, amphipods and
smaller fishes.

48. Reference
• A text book of fish biology and fisheries by Dr. S.S Khanna & Prof. H.R
.Singh
• Marine Fisheries of India by D V Bal & K V Rao
• E-course:-Unit 1: Finfish and Shellfish Food and Feeding Habits
• Wikipedia
• www.Fishbase.com