1. How Aquariums Are
Their Own Ecosystems
(using my own aquariums as an example)
By: Alyssa McPherson
2. My first aquarium was when I was about 7
years old, I had some basic easy to maintain
fish with a couple of artificial decorations.
Now, I am 18 with 4 different aquariums,
with 8 plants and over 50 fish. Most people
are not aware of how much science it is
behind keeping a sustainable aquarium or
‘ecosystem’.
3. Biodiversity of Species
When you think of the word ‘ecosystem’ you should think of
all the different species relating to each other on a food web or
a food chain. Aquariums can work this way too, depending on
how they were set up. Some common biotic things that are
found in aquariums are:
•Fish
•Plants
•Invertebrates
•Algae
•Bacteria
Algae can be found growing on
decorations and sides of the tank
4. How Species relate to each other
1. Bacteria (a.k.a. beneficial bacteria) is mostly found in the filter of the
aquarium, where it eats fish waste and releases a less harmful
compound
2. Algae blooms appear when there is an excess of waste or a change in
the water chemistry. They also grow rapidly when there is too much
light.
3. Invertebrates are useful to the aquarium because they typically eat
left over food. They can also potentially burrow in the substrate and
release gas bubbles which can be harmful if left too long.
4. Plants use CO2 and produce O2 for fish to breath. They can also
filter the water of pollutants. Some plants are even a tasty snack for
fish.
5. Depending on the fish, they will eat algae, plants, or the food that
you can buy at the pet store.
5. The Gas Exchange
Fish need O2 in the aquarium to
breath (yes, they can drown!).
There are many ways how gases
like O2 and CO2 move around in
an aquarium. One of the main
places that this exchange
happens is actually at the surface
of the water by osmosis. Another
important way of transferring
gases is by a filter or bubbler.
OSMOSIS: a process by which
molecules of a solvent tend to
pass through a semi permeable
membrane from a less
concentrated solution into a more
concentrated one, thus
equalizing the concentrations on
each side of the membrane.
-Dictionary.com
6. Filters
The filter is acts like the ecosystem’s lifeline. The filter is the main
storage for beneficial bacteria, one of the main contributor to oxygen and
carbon dioxide into the water, and removes toxins like fish waste and
leftover food.
Filters can typically be divided in 3 different
parts: Mechanical, biological, and chemical.
The mechanical part is usually a large sponge,
its job is to collect large parts of debris.
The chemical part is activated carbon, which
collects waste on a micro scale
The biological part hosts most of the beneficial
bacteria where ammonia is eventually broken
down to nitrate
7. The Nitrogen Cycle
Why do we have to do weekly water changes? Simply because of
the nitrogen cycle. Fish waste, plant decay, and leftover food are
polluting the water with ammonia (NH3). The beneficial bacteria
consume the ammonia and produce nitrite (NO2). Then other
bacteria go further and turn nitrites into nitrates (NO3). Nitrate is
far less harmful then ammonia, but can lead to diseases if left
untreated. This is why we do water changes.
9. 1. Betta fish can live in tiny bowls
Betta or ‘Chinese fighting fish’ is the most hardy fish that people
keep as pets. They are tropical which means they need to be kept in
water around 78ºF. They also need filters, to remove the ammonia
that they produce. Ammonia is deadly to all fish, betta fish are no
exception, and will chemically burn their slim coat and their
respiratory system.
In small bowls, betta fish will live
for a few years because they are
hardy fish. With the right care,
betta fish can easily live over 10
years!
10. 2. Betta fish have to be by themselves
Male bettas are very territorial of their home and will fight other male
bettas over dominance. However, that does not mean that they have to be
solitary. Bettas will only fight other species if they resemble another
betta. Snails, shrimps, frogs, and some minnow-looking fish are great
companions and bettas will not see them as a threat. Females are a lot
less aggressive than the males and can even be grouped together.
Male bettas have large fins while females have smaller fins
11. 3. Fish grow to the size of their tank
On the contrary, fish will grow to
the size they were meant to grow
to. Many people believe this myth
because there is some truth behind
it. Fish will only grow if they are
healthy. When the fish is too big
for its environment, the filter will
not be able to keep up with the
waste, leaving the water polluted. If
the water is polluted with waste,
then the fish will be sick and will
not grow.
12. 3. Any kind of “algae eater” eats algae
There are many types of algae eaters, I own a common pleco, an orange
bristlenose pleco, and a cory cat. Only one of which actually keeps up
with the aquarium’s algae growth. Can you guess which one?
13. Bristlenose Pleco
My bristlenose pleco eats so much
algae that I have to feed her extra as
well, as you can see shes eating some
zucchini as a treat.
14. Fun Facts:
My African Cichlid are having fry!
A lot of African cichlids are mouth-
brooding fish which means that they
will hold the fry in her mouth until
they are ready to be on their own.
Notice how the fish on the right
seems to have a swollen and dark-
coloured jaw? It means she's carrying
fry! Another one of my fish have
already had babies, how many can
you count?
Fry = baby fish
15. Fry are very tiny when they are
first released, as you can see a baby
compared to its mom, and again
compared to my pinky nail
16. Now I challenge you!
Create your own ecosystem! Could be very simplistic,
with just a simple potted plant and bugs. Or complicate
it to a unique biodiversity of species! Make sure to have
at least 2 different organisms that depend on each other
in some way. Then ask yourself:
1. How much effort is needed to maintain it?
2. How do these species relate to each other?
3. What else is needed in order for this ecosystem to
become a complete biosphere?
