The Emperor Tetra, Nematobrycon palmeri, is a beautiful fish. It is one of the larger Tetras, growing to about 8 cm as a maximum, although one this large is unusual. It comes from streams and rivers of western Colombia including The Rio Atrata and The Rio San Juan. This is a tropical area, and the Emperor Tetra is a tropical fish. I suggest heating them with a standard aquarium heater with the thermostat set at 24̊ C.
I have searched for information about this fish, and have found it even more contradictory than usual. Therefore, the information in this fact sheet is based mainly on my own experience in keeping and breeding The Emperor Tetra.
Feeding and Keeping
The Emperor Tetra is an omnivore, eating both animal and vegetable food. Any good flake or pelleted fish food is a good basis for its diet. They will benefit from live food like Daphnia and wrigglers (Mosquito larvae) as well as frozen fish food.
The Emperor Tetra is a fairly easily kept fish which is a little less fussy about its water conditions than many tetras. It does not school as readily as most tetras, and a single fish, or a pair appears happier than with most tetras. The males and females are easily told apart. There are many differences, but I find the easiest one to be sure of is the tail. The male has a three-pronged tail with the centre, black, part extending beyond the rest of the tail while in the female, the centre black part only reaches as far as the clear part of the tail.
They can be kept happily even in the unusual water supplied by the water company to consumers in the Adelaide Hills as long as you get rid of the dangerous level of Chloramine, and adjust the pH to about seven. Although coming naturally from water which is softer and more acid than this water they will live and breed in it.
I have found them easy to breed. However, some people consider them a difficult fish, and I would caution that I am only writing about small scale breeding for interest, not about large scale commercial breeding.
I suggest this set up for breeding. Use an aquarium of at least fifty litres capacity, and preferably bigger. Plant it heavily so that there are many dark hiding places. Put a good-sized pair of Emperor Tetras in and feed them well. Daphnia is an excellent food. This can be supplemented with any good dry fish food and with frozen food like blood worms.With reasonable luck, the fish will spawn and some of the babies will survive. In my experience, the parents are not very cannibalistic. The babies will find some useful natural food in the form of protozoa, algae, etc. Screened Daphnia will provide them with more nourishment as they grow, and dry fry food like the HBH food, ‘Fry Bites’ is another food that can be used.