By Shahu Sardar*
Stocking an aquarium not just refers to adding fishes into the tank, but it is far more than that. Properly planned stocking is very useful. This small step helps avoid common problems like overstocking, water imbalance, fights for territories, and stress in fishes and gives your tank a healthy and happy environment. And people overlook this but later have to tackle the above problems within few days after adding the fish.
So here how to add the right live stock into an aquarium:

The Number of Fishes
Before you start stocking you would like to know how many fishes can fit into your tank without overstocking. Here are some things to consider:
- Follow the 1 inch per gallon fish rule. If a fish is 1 one inch in size, it needs roughly 1 gallon/3 liter.
- Consider how big the fish will get as time passes. Like the Neon tetras grow at most 1.5 inches, whereas angelfishes can get up to 6 inches long. Obviously, you can add more tetras than angels in the same tank.
- Leave enough space to swim per fish.
- Take into consideration the space that would be taken up by decorations, plants, rocks, etc.
- The bigger the fishes will get, the more extra swimming space they will need.
Also after adding the fish, you can carefully observe whether each fish is comfortable swimming through the tank.
Swimming Level
Many fishes swim at a particular part of the tank. The water regions in a tank are the bottom-level, Middle-level, and Top-level fish. The fishes belonging to the particular level will spend most of their time in that region. So it is important that the tank has the fishes from this particular level, and not much fishes are put together in the same level.
Fishes swim at any level:
- Zebra danios
- Rosy barbs(suggested)
- Pearl danios
These fishes can be added in small quantities and will keep swimming throughout the tank.
Top-dwelling fishes:
The top-level has the least decoration, so you could add more colourful species here. Their mouths are generally upside facing. They generally are carnivores and should be given high protein diet. Also, these fishes are generally high jumpers. Sudden vibrations, fights or stress can make them jump high and can come out of the tank, so a lid is suggested.
- Betta fish.
- Gouramis.
- Guppies. (suggested)
- Mollies
Middle Dwelling fishes:
This category has a huge variety and is easy to choose from. They spend most of their time in the center column, and thus should be colorful or should have good/unique fin shapes. The best mid-dwelling fish is the Angelfish, which makes the centerpiece of any aquarium. These have simple color patterns, with their unique fin shape and graceful swimming style. You can read about them more here: Angel fishes. Along with this schooling fish are suggested as they create a good contrast with the angel fish’s slow swimming.
- Neon tetras(at least 10+)
- Angelfish(suggested)
- Tiger barbs.
- Rainbowfish
- Discus.
Bottom-dwelling fishes.
This includes fishes that spend fish of their time at the bottom. Their mouths are generally downside. And they need special sinking pellets. Even though being at the bottom, they become a superb addition to the tank. Many of them include the cleaning crew fishes, which eat up algae, or uneaten food in the tank. Add them in any tanks helps to keep the tank free from algae.
- Plecos(not suggested)
- Catfish
- Red-tailed black sharks
- Corydoras.
- Siamese alga eater.(suggested)
Choosing Get Along Species
A community tank, is a tank where 2+ species live together in the same tank, but for many it’s just about keeping random fishes together. If randomly fishes are added to a tank, it will soon result in deaths of one species, or territorial fights. Being a community tank, the species should get along well.
When getting any fish know the temperature, pH, and other requirements of that fish. And check if they are similar to other species you have in the tank. Here are some examples.
Angelfish are tropical warm-water fish (24-30 C), whereas goldfish are cold-water fishes (20-24 C) so they can’t be put together. Tiger barbs are known to nip long-finned fishes. So adding angels with them would not be a great idea. Plecos get massive in a short time. So other bottom dwellers are always a better choice.
By this we can categories the tanks into two types, Tropical tanks and Temperate tanks. Tropical tanks are warm-water tanks with lots of plants and equipped with a heater. And the temperature is usually at 26-32 degree Celsius. Fishes that can be added are: Angels, Gouramis, Cichlids, etc.
Whereas the temperate tanks are cold water tanks where temperature is maintained around 20-24 degree Celsius. These are with relatively less planted and more free swimming space is provided. Fishes added are: Goldfish, Pearl danios, Koi, Rosy barb etc.
*Shahu Vijay Sardar is a teenage Aquarium hobbyist from India. Shahu started fish keeping at age of 6 and started AquaNation blog so as to educate people about the aquarium hobby. His aquarium blog: www.aquanationurl.blogspot.com