The right fish for your aquarium
From the over 30,000 fish species of the world in fresh and marine water only a tiny part is regularly kept in aquariums. Since an animal species has never been wiped out by pet keeping and not even the world’s most caught aquarium fish, the cardinal tetra, has ever been endangered in its stock by its millionfold capture (stock figures in nature unchanged for decades), we shouldn’t feel guilty about keeping fish in aquariums. More and more fish and invertebrate species have been bred, so that there is no need to remove them from their natural habitats. Unfortunately some fish species exist only in aquariums because their natural habitats have been destroyed. In such cases catching aquarium fish can count as active nature conservation, because the fish catchers are helping fishing areas (i.e the habitats) remain intact to secure their livelihood!
We aquarists divide fish in three main groups: freshwater fish, marine fish and brackish water fish, which live in freshwater and marine water biotopes, as well as in the regions in between.
Which fish fit into my aquarium?
Fish communities in the aquarium: Which aquarium fish do NOT go together and why? Which criteria should you follow when selecting fish? What demands do aquarium fish make on your aquarium and how high maintenance are they? We explain which fish go together and why certain fish species do not.
When selecting your aquarium stock please take the following points into account for each fish species:
Is your aquarium large enough? Some sucker catfish (as an example) can become 30 cm long! Are the fish sizes of different species compatible or does one species regard another one as food?
Highly active fish (e.g. rainbow fish) need a lot of space and long aquariums. High-backed fish (e.g. angel fish) need high aquariums.
Way of life
Do your fish (a lot of cichlids, as an example) need hiding places? Do they need wood (as many sucker catfish)? Do they dig and need soft soil (e.g. armoured catfish, loaches)?
Are the fish territory-forming (as are many cichlids)? Do you need to keep them in pairs, in a harem or in a shoal? How well can the fish be socialised with your other fish species?
Do the fish need highly specialised food (e.g. puffer fish often eat ONLY snails)?
Are they plant-eating fish (e.g. long-whiskered cat fish, Leporinus tetras)?
Do the fish have special demands on the water quality (e.g. discus fish prefer pH values below 7.0)?
Do you need to fully cover the aquarium because your fish like jumping?
The most important orders and families in freshwater aquatics
Of course, there are still more families and orders, such as armed spiny eels, Asiatic glassfishes, snakeheads, gobies etc. If you decide to keep one of these fish, please find out what demands the animals have on aquarium size, water, socialisation and food.
Livebearing tooth carps
Egg-laying tooth carps
Brackish water fish
Brackish water fish live in the area between marine water and freshwater. The salinity of the water is therefore a value between that of marine water and freshwater. Although the animals tolerate both extremes (marine water/freshwater) they mostly feel more comfortable in midrange values in the long run. Some species migrate from marine water to freshwater and the other way round. Keeping aquarium plants is impossible because of the salinity. Only mangroves tolerate the required and fluctuating salt concentrations. Fish in brackish water have quite special needs and should only be kept by experienced aquarium owners.