To increase the chances of your fish being compatible you need to consider the fishes’ territory. Fish swim in different zones of the aquarium. Some swim near the surface. Some swim midwater. And yet others stay near the floor of the aquarium. Generally fish in one zone will be less territorial with fish from another zone.
Here I will list suggested fish groups by tank size with an eye on maximum compatibility.
2 foot 50litre tank
Small amazonian biotope
4 hatchetfish Midwater fish
8 neon tetras
2 angel fish Bottom dwellers
4 panda corys
Caring for catfish, loaches and other bottom-feeders
While bottom-feeding fish like catfish can be some of the most fascinating specimens in a tank, they often go underappreciated by the aquarium community in favour of more standard species. This is a shame because catfish and other bottom-feeding fish offer very real benefits for their owners.
Benefits of keeping catfish and bottom-feeders in a community tank
They exhibit unique and fascinating behaviour not seen in other types of fish
Bottom-feeders are great at cleaning up tank debris and detritus left over by other fish
Some species of catfish will eat algae, making it easier to control your tank’s algae problem
They make great tank mates with a wide variety of fish, and spend most of their time conveniently out of their neighbours’ business, minimising conflict
Catfish are generally very hardy and can adapt to wide variety of water conditions, even poor water conditions.
Choosing bottom-feeders for your tank
There are a huge number of different types of catfish and other bottom-feeding species that you can introduce to your tank. Different choices will work better depending on the size of the tank, the type of substrate you use, and the other fish you keep. Since some species of catfish can grow very large while other catfish are schooling fish, it is important to be sure you choose a species that will not overwhelm your aquarium.
By far the most popular bottom-feeding fish are plecostomus catfish, corydoras catfish and loaches. Both catfish are total scavengers who will eat just about anything including all the algae in your tank, keeping it pristinely clean without requiring any maintenance work. The main difference is that corydoras rarely grow more than a few inches long, while plecostomus can grow up to 2 feet (60 cm) long, quickly overwhelming the tank!
If you have a tank that can support a plecostomus catfish, however, you can consider all of your algae problems history, since its voracious appetite and constant feeding will keep your tank clean for as long as the fish lives. Another great benefit that plecostomus offers is a long life span: twenty to thirty years in some cases!
If you favour novelty in your tank, there are some species of catfish that offer this: the kryptopterus catfish, also known as the glass catfish, has transparent skin that actually allows you to see straight through it: bones, organs and all! This fish is not for everyone—they are very delicate and will generally only eat live food, but offer an immensely gratifying and eye-catching aquarium display.
Loaches are also very popular, and are highly desired thanks to their distinctive colouration and personalities. Loaches do their best in small groups where you can enjoy observing their complex social behaviour. They are active fish, and will constantly be turning over your sand or gravel substrate looking for debris to eat. They tend to be peaceful and do well in community tanks.
If you would like to add bottom-dwelling catfish or loaches to your tank, you should carefully consider their compatibility with your tank and your current fish. While catfish and loaches tend to be very peaceful fish, they can get aggressive if bullied, and large, carnivorous catfish may eat small fish up to half their size.
You will want to identify whether the catfish or loach you would like to introduce likes to be kept in a school or alone. Zebra plecostomus, for example, is a very popular and beautiful fish, but one that prefers to be the only bottom-feeder in a tank.
Being bottom-dwelling fish, your catfish and loaches will enjoy soft substrates that they can easily sift through—high quality sand or small, polished gravel works best. Keeping some flat-lying rocks for them to sit on can be a great aquascaping move, as well, especially if you keep a small school of bottom-dwellers.
Caring for catfish and loaches
While bottom-feeders will happily clean your tank of algae and eat just about any debris that may make its way to their habitat at the bottom of the tank. This may not be sufficient food for them. So these fish need to be fed, too. And, you should be careful to monitor their health and appetite closely because they are easily neglected by their owners.
Catfish of the corydoras family are often called armoured catfish because they feature hard exterior scales that function like a suit of armour. With these fish, starvation can often go unnoticed since the hard plates will not shrink noticeably, but the fish inside the scales will.
Another important element of care for catfish, loaches, and other bottom-feeding fish is their sensitivity to medication. Although most of these fish are very tolerant of poor water conditions, they are extremely sensitive to the side effects of medication. If you need to use medicine in your aquarium, it is best to move your catfish or loaches to a quarantine tank temporarily.
If you follow the above guidelines and take good care of your bottom-dwelling fish, you should have a beautifully clean, algae-free tank thanks to the nature’s bin men and cleaners of the aquatic world. So throw away your algae scrubber!