Often confused with the Emperor Tetra (Nematobrycon palmeri), but they are easily distinguished by the fact that Inpaichtys kerri possess an adipose fin and have smaller size. The male has a light blue back and its adipose fin is also blue. A broad iridescent dark blue stripe extends from the snout through the eye and to the caudal fin base, while the belly is silvery-blue. The female is less colourful, but has a reddish or orange adipose fin. There is also a Super Blue color variant.

Females have stockier and less colorful bodies, and they also have a red adipose fin, while males, have blue adipose fin.

For breeding a small separate tank is enough with a few clumps of fine-leaved plants such as java moss or some kind of mesh with a large enough grade so the eggs can fall through it and can protect the eggs from the adults. The aquarium should be very dimly lit and the water should be acidic (pH 5.5-6.5), very soft (1-5 dGH) with a temperature of 24-27 °C. Filtering the water through peat is also useful, as it mimics their natural habitat. They can be spawn in pairs or in a small group, but either case condition them with plenty of small live and frozen foods. When conditions are to their liking the fish should begin to spawn the following morning. The parents will eat the eggs, so after spawning they should be removed from the tank. The yellowish eggs hatch in 24-48 hours, and the larvae become free-swimming after another 3-4 days. The fry can be fed with very small live foods or with liquid fry food. The number of the eggs can be 100-150. The fry grow quite quickly, with proper feeding they can reach 3-4 cm in length within 6 months.

Scientific name: Inpaichthys kerri (Géry & Junk; 1977)
Synonyms: Blue Emperor Tetra, Royal Tetra, Kerri Tetra
Common name: Purple Emperor Tetra
Group: Characins
Distribution: South America; Brazil, in the Rio Aripuana, and upper Rio Madeira
Size: Male: 4 cm, female: 3 cm
Biotope: Inhabits slow-flowing black water tributaries in forested areas, where the water is very acidic and stained brown because of decomposing organic matter.
Social behavior: A peaceful fish, that souldn't be kept with more boisterous or much larger tankmates. It can be fin-nipping, but it only tends to exhibit it when kept in insufficient numbers.
Diet: Omnivorous; not a picky eater, it will eat all kinds of dried foods, but should also be offered regular meals of small live and frozen foods to maintain its color and development.
Breeding: Quite hard
Tank: Minimum 70 litres
Population: 5-6 fish for 70 litres
Decoration: A biotope setup would be very simple to arrange: use river sand as substrate and place some tree branches or roots into the tank. A few handfuls of dried leaves would complete the natural feel. They like darker aquariums, so use some floating plants to subdue the lighting and use peat-filtered water.
Temperature: 24-27 °C
pH: 5.5-7.0
Hardness: 1.0-12.0 dGH
Lifespan: 4-5 years

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