Understanding how to identify different types of fish can be a fun and useful skill. It involves looking at the physical features of the fish, which have evolved over a long time to help the fish survive in different water environments.
This can also give you an idea of what kind of environment the fish needs to live in if you’re setting up a fish tank. This method of identification is usually accurate about 95 percent of the time.
Here are five things you should look at when trying to identify a fish:
- Body Shape,
- Mouth Location,
- Scales,
- Fish Color, and
- Swim Bladder.
By looking at these features, you can get a basic understanding of what kind of fish you’re looking at and what it needs if you’re trying to create a suitable environment for it in a fish tank.
Let’s now take a closer look at each of these.
1. Body Shape
By looking at the shape of a fish’s body, you can learn a lot about it. If a fish is shaped like a bullet or is sleek, it usually lives in open water.
On the other hand, if a fish is flat or has a deep body, it typically lives on or near the bottom of the water.
Here are some examples:
A fish with a streamlined body, like a zebra danio, is built for moving quickly through open water with sudden bursts of speed. You wouldn’t find such fish in stagnant or slow-moving waters.
Some fish have a tapered body shape, like a discus, which helps them move swiftly between obstacles like tightly packed roots. This shape reduces water resistance, allowing the fish to preserve energy.
These types of fish are typically found in areas with natural barriers like sunken tree roots.
Fish with round bodies, like fancy goldfish, are not very fast swimmers and get tired quickly. They prefer slow-moving waters.
Lastly, fish that are flat on their bottom side, like the cory, usually spend most of their time moving along the bottom of your aquarium.
With these characteristics in mind, you can identify different fish and understand their natural habitats and behaviors better.
2. Mouth Location
Fish have different mouth shapes and positions that indicate their feeding habits and where they usually hang out in the water.
Top feeders, like the hatchet fish, have mouths that point upward. This means they eat food that floats on the water’s surface in the aquarium. Imagine them scooping up flakes like a ladle!
Midwater feeders have mouths that face straight out from their face. Goldfish and platys are examples of these. They eat by catching food as it sinks in the water. Think of them as the snackers who grab and go!
Bottom feeders, like catfish, have mouths that point downward. They like to eat food off the aquarium floor, the glass walls, and even from flat rock surfaces and plant leaves. It’s like they’re vacuuming the bottom of the tank for food!
3. Scales
Most fish have bodies that are covered with scales. These scales overlap or cover each other in a way similar to how the tiles on a roof do.
And just like how the tiles protect the roof from things like rain or snow, these scales protect the fish.
They also help the fish to glide smoothly through the water, like a sleek sports car.
To add to this, there’s a slimy layer on top of the scales that makes them even smoother and protects the fish from nasty things like bugs and germs.
But, not all fish are the same. Some don’t have scales. And even amongst those that do, there are different types of scales:
- Ctenoid Scales: These are like tiny little teeth on the edges.
- Cycloid Scales: These are smooth and round like a pebble.
- Ganoid Scales: These are diamond-shaped and can be found on certain fish like gars.
It’s interesting to note that scales grow from the skin of the fish and they don’t have any color.
All the colors you see on a fish’s scales actually come from pigment cells in the fish’s skin. And on that note, let’s talk about fish color.
4. Fish Color
Fish get their color from special pigment cells in their skin called chromatophores.
There are three main types of chromatophores:
- Melanophores: These cells give fish darker colors, like black, brown, and blue.
- Xanthophores: These are the cells that produce the red, yellow, and orange colors you see in some fish.
- Iridophores: These cells reflect light, and that’s why many fish have a shiny or silvery appearance.
So, in simple terms, these three types of chromatophores give fish their amazing variety of colors.
These colors are not just for show; they have important functions like scaring away fish that might want to eat them and attracting fish they might want to mate with.
This is still the case even for fish that live in tanks at home. In fact, some types of fish that live in freshwater and semi-salty water have developed new colors as a result of selective breeding, and they use these colors to get ahead in things like mating and showing dominance.
The lighting in your fish tank can affect your fish’s color. If the light is too dim or too bright, your fish may look less colorful.
Their diet and their stress levels can also affect their color. If they’re not eating well or if they’re stressed, their colors might not be as vibrant.
5. Swim Bladder
Fish are a little bit heavier than water, so you might think they would always sink to the bottom of your fish tank. But fish have a special organ called a swim bladder that helps them float.
You can think of a swim bladder like the floaty vests that scuba divers wear to help them float.
The swim bladder is filled with gas and can get bigger or smaller. When the fish wants to go up, it makes the bladder bigger by adding more gas. When it wants to go down, it makes the bladder smaller by letting out some gas.
This way, the fish can stay at any level in the water without having to swim all the time.
Just like we breathe out carbon dioxide, fish can also let out gas through their gills. They use the gas in their swim bladder to keep them from sinking or floating too much.
When they want to go down, they squeeze their bladder to let out some gas. And when they want to go up, they let more gas into their bladder.
Some fish that live on the bottom of the water don’t have a swim bladder. But most fish use this amazing organ to move up and down easily without using too much energy.
