Stocking rate & other fish

Population density and companion fish in a discus aquarium

N B: A group of discus fish should contain at least 10-12 fish.

This recommendation should be adhered to absolutely, otherwise an animal night be excluded from the group and will not receive enough food.

Our recommendation for the population in an aquarium with a tank size 100 cm x 40 cm x 45 cm (c. 180 litres)

10-12 discus fish (8-10 cm in size). Fish of this size are very robust and are relatively moderately priced. This size of aquarium is sufficiently large for the fish when they are mature (they can reach a size of 20 cm in diameter). Since discus fish can live up to 15 years and are fully grown at 1 ½  years old, you can be sure that your purchase will be worthwhile. You can have any combination of colours in your discus group, e.g. a discus group of 2 fish each in six different colours, or you can stay with one colour.

The Germany Veterinary Association for the Protection of Animals (tierärztliche Vereinigung für Tierschutz e.V. - TVT) recommends the following for keeping fish
in pet shops:


a maximum of 45 fish (8 cm) per 180 litres or
a maximum of 12 fish (15 cm) per 180 litres.

Ask your specialist stockist if the discus fish on offer were caught in the wild, come from Asiatic breeders or are our own STENDKER discus fish (if this is not immediately clear). You should choose onlyone of these three types and not mix them since discus fish cannot be mixed from different breeding stock.

Companion fish for your discus aquarium
With the above tank size, 180 litres of water and a group of 12 discus fish (8 cm) you can add the following companion fish to make your discus aquarium more varied and more interesting:

Neon school comprising c. 50-80 fish

Butterfly cichlids (pair) c. 2-3 pairs

Dwarf cichlids c.6 fish

Catfish (small bushy-nosed catfish are also called window cleaners) c. 6 fish.

Scalar fish (do not use, or only use after full treatment for tape worms), c. 4 fish

It is a good idea to add a coconut to your aquarium as a breeding/hatching area for the pairs of butterfly cichlids. Butterfly cichlids display very attractive mating and parenting behaviour.

The bushy-nosed catfish can prove useful cleaners in your discus tank. However, take care to select small catfish since catfish over 15 cm like to "nibble" discus fish, something to be avoided preferably.

Scalar fish are also popular companions for discus fish. We advise against it because scalars are generally infected with tape worms; the scalar manage very well with them but tape worms cause discus fish major problems. However, if you don't want to do without scalar fish in your discus aquarium, always treat the scalar fish for tape worms as described in the last section in this chapter.


Always buy all your discus and companion fish from the same shop and as close together as possible since fish bought later may introduce disease and other bacterial strains into the aquarium. To protect your fish population we recommend buying enough fish at the beginning and do not add fish later. This will save you a lot of trouble and will avoid the risk of disease being introduced.

Exception: If you purchase our STENDKER fish, you can add fish of varying sizes and colours at any time from our breeding operation.

Quality check for companion fish (freshwater ornamental fish departments in pet stores)

Visit several pet shops before you decide to buy fish and check the quality and state of health of the fish on offer as follows:

1. Do the fish look healthy?

2. Do the fish still look healthy on your next visit, c. 2 weeks later?

3. Do all fish reach the food when being fed and do they have a good appetite?

A further mark of quality for a healthy discus fish is its bright red or amber-coloured eyes and a wide forehead (that is where the reserves of fat are stored).


Treating scalars for tape worms
Tape worms will impact the health and growth of discus fish considerably. Our STENKDER discus fish are free of tape worms but are unlikely to remain so if you add these companion fish. In our opinion the only option, if you do not want to dispense with scalars as companion fish, is to treat them for tape worms beforehand and only add them to the discus fish after completing

the treatment.
Treatment for tape worms for scalars
Use tremazol or other medicines based on praziquantel and follow the instructions.