Fish species

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.

The selection

When selecting your aquarium stock please take the following points into account for each fish species:

Fish size

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?

Behaviour

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)?

Aggressiveness

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?

Food

Do the fish need highly specialised food (e.g. puffer fish often eat ONLY snails)?

Plants

Are they plant-eating fish (e.g. long-whiskered cat fish, Leporinus tetras)?

Water

Do the fish have special demands on the water quality (e.g. discus fish prefer pH values below 7.0)?

Aquarium design

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.

Cyprinids

The cyprinids include some very popular aquarium fish, such as barbels, danionins, koi (pond fish), red-tailed black sharks, white cloud mountain minnows and also the sucking loaches.

Loaches

Loaches are very active fish which are kept individually or in shoals.

Tetras

The tetra group includes small peaceful representations, such as the neon tetra, as well as large carnivores like the piranha.

Catfish

This order includes huge predatory catfishes, as well as small popular species, such as armoured catfish or dwarf suckers.

Rainbow fish

These magnificent and lively fish from Australia are shoal fish which need a lot of space for swimming.

Livebearing tooth carps

The most popular ornamental fish at all, such as the guppies, platties and black molly fish belong to the viviparous tooth carps.

Egg-laying tooth carps

A lot of egg-laying tooth carps have incredibly beautiful colours and don’t become large!

Cichlids

The cichlidae family (cichlids) include totally different types of fish: peaceful small dwarf cichlids, high-backed angel fish, high maintenance discus fish, undemanding zebra cichlids, mouth brooding forms from Lake Malawi and Lake Tanganyika and very large growing predators like the velvet cichlid.

Labyrinth fish

Since many labyrinth fish live in hot, low-oxygen water they have developed an additional respiratory organ, which is called labyrinth.

Blowfish

These must be the cutest aquarium dwellers of all!

Further species

Of course, there are still more families and orders, such as armed spiny eels, Asiatic glassfishes, snakeheads, gobies etc.

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.

Scats

Juveniles and middle-sized animals don’t like freshwater and need to be kept in brackish water.

Monos

Juveniles and especially adult fish require brackish water, but can also be kept in pure marine water.

Mudskippers

Since mudskippers spend a lot of time outside of the water, a large land part with soft substrate is required.

(Many) puffer fish

Puffer fish can attain many different sizes but most species need brackish water or marine water.

Banded archerfish

Only very few banded archerfish species can be found in pure freshwater.