Our tropical fish come from all over the world, coming from many habitats and different water types. Some stay tiny like the diminutive Pygmy rasbora, while others grow huge like Redtail catfish.

If tropical fish can be housed together in the same tank without fighting, eating or killing each other they are termed “community” species. Most first-time fish keepers aim for a community tank i.e an aquarium filled with many different shapes, colours and fish behaviours. Community tanks are the most popular type of tropical aquarium and community fish, the most widely available, and the biggest sellers. 

Popular community fish species include Guppies, tetras, danios, rasboras, some barbs, rainbowfish, Bristlenose catfish and Corydoras catfish.

Accidental fish eaters

Some fish are only suitable for community tanks when small. They are peaceful but grow disproportionately to other species in the tank, and although not out and out predators, large specimens may well eat small species like Neon tetras, given the chance. Examples of this include Silver sharks and Angelfish - very popular in the shops but ultimately only suitable for community tanks containing medium and large-sized fish. 

Fin nippers

Tiger barbs are the most famous fin nippers by far. Everybody wants them but they will nip the fins of other popular long-finned fish including Angelfish, male guppies and male Siamese fighters. But other unassuming fish can be fin nippers too. Avoid Serpae tetras, Blue tetras and Skunk Botia. Many fish have the potential to become rogue fin nippers although this may be down to overcrowding, too small a tank, not being kept with enough members of their own kind or simple hunger

In the wild, there are even specialist fin-eating fish, which have evolved to eat the fins of other fish when other food is scarce. Many wild fish can counter this though by producing expendable tail fin extensions and even markings with “eye spots” on to make the tail look like the head. Fins can be regrown and it’s better to have a predator bite a fin and you survive to swim another day, than bite flesh and the wound be fatal. The fascinating world of fins...  

Territorial fish

Territoriality is a trait that some fish species bring with them from the wild. Food is naturally scarce and no fish really knows where its next meal is coming from. One way to combat that is to be more aggressive than others around you, chasing them away from where you are so that when and if food comes along, you’ll be the first to eat it. This happens with predatory fish too, where they don’t like living next to each other as the fish next to you will eat all your prey. Chase them away and the problem should go away.


Territoriality can also arise in herbivores. Algae eating species need a patch of rocks where algae can grow. If others of your own kind come along and eat your algae there will be nothing for you, so it's worth fighting for. This kind of territoriality can be seen in sucker mouthed catfish, Chinese algae eaters, freshwater “sharks” like redtail black and red finned, and even algae-eating cichlids like the Mbuna from Lake Malawi and Tropheus from Lake Tanganyika. 

Transfer these to the confines of an aquarium and they will chase fish out of their area just like they would in the wild. But if the tank is too small for others of their own kind to get away harassment can be constant, causing stress, injury and even death. That’s why only one specimen of a territorial species like the red-tailed black shark is recommended per tank, and if it starts to chase other fish it needs a bigger tank, more grazing opportunities and less similar-looking fish.


A biotope is an aquarium set up and stocked to represent a particular habitat in the wild, like the Rio Negro in Brazil or lake Malawi in Africa. The most popular biotopes are general South American ones, although a purist would argue that South America is too huge and too varied to be represented in just one tank. 

Biotopes are aquascaped and stocked to look as if they are being observed underwater in the wild. A blackwater Rio Negro biotope would have just sand, wood and leaves, with tannin-stained water and fish that come only from that river like Cardinal tetras. A properly done biotope can look visually stunning as well as reassuring the owner that the fish are living as close to wild conditions as is possible for an aquarium including pH, temperature, decor and tank mates. Give fish biotopic conditions and they may behave more naturally, produce better colours and even breed. Although many Cardinal tetras are farm bred and have never seen the blackwaters of the Rio Negro. 

Frequent biotope faux pas includes stocking fish or plant species that don’t actually come from that lake or river, fish that although biotopically correct, would outgrow the tank, or fish mixing fish that live together in the wild, but as predators and prey. The Rio Negro river is also home to Peacock bass, Arowana, Discus, Angelfish, Stingrays and Piranha, but you wouldn’t house them together in an aquarium, or with Cardinal tetras!

Species tanks

A species tank is one that contains just one species of fish, be it an individual or a group. Species tanks may be necessary for fish species that are aggressive or territorial or need specialist feeding or water conditions. But you could just set up a species tank for your favourite fish, like Congo tetras for example. 

A tank with just red-bellied piranha would be classed as a species tank, as they aren’t recommended to be mixed with anything else for obvious reasons. Black piranha can’t even be mixed with their own kind, so a Black piranha species tank would contain just one fish.


Some community fish are peaceful but simply grow too large. Common plecs, Silver sharks, Tinfoil barbs and even Clown loach all grow to over 12”/30cm in length, meaning that a community containing those should really only be over six feet in length, with filtration to match. Tankbusters are species that grow huge, and although peaceful, Pacu and Ripsaw catfish grow to over three feet in length, requiring a tank over three feet wide just to turn around! Redtail catfish, Tiger shovelnose, Giraffe catfish, Giant gourami, Arowana and Pangasius are just a few common tankbusters. Due to massive eventual size, they should only be housed and viewed in public aquaria and zoos.      

Peaceful communities

So a community tank should contain peaceful fish which get along together. They don’t all have to be from the same country, river system or continent, and many community tanks contain tropical fish species from South America, South East Asia and Africa. You can see from the lists above that an average community tank containing Neon tetras, Guppies, Tiger barbs, Angelfish, Silver sharks, a Redtail black shark, Common plec and Clown loach will quickly run into problems, and for a number of reasons. But here are just a few species that are known for small to medium size, ease of keeping, availability and generally good, community behaviour:

  1. Neon tetra
  2. Cardinal tetra
  3. Congo tetra
  4. Black neon tetra
  5. Lemon tetra
  6. Rummynose tetra
  7. Harlequin rasbora
  8. Dwarf gourami
  9. Honey gourami
  10. Checker barb
  11. Pentazona barb
  12. Rosy barb
  13. Cherry barb
  14. Golden barb
  15. Guppy
  16. Platy
  17. Swordtail
  18. Molly
  19. Ram 
  20. Neon dwarf rainbowfish
  21. All Corydoras
  22. Otocinclus
  23. Bristlenose catfish
  24. Danios
  25. White Cloud Mountain minnow  

For more information on live-stock, our Shop team is best recommended to offer support and advice on compatible aquarium fish. Tropical fish can be tricky to house, but if unsure, there is no harm in asking for an expert's advice on a suitable tank set-up. Feel free to reach out if you need support or assistance.