Kerri tetra - Impaichthys kerri

Kerri Tetra (Inpaichthys kerri)

The Kerri Tetra is a beautiful small South American tetra, admired for its subtle blue to purple sheen, peaceful nature and active shoaling behaviour. Also known as the Blue Emperor Tetra or Purple Emperor Tetra, this species looks especially attractive in planted aquariums with darker substrate, soft lighting and open swimming space. It is a peaceful community fish, but it is best kept in a proper group so that males can display naturally and the shoal remains confident.

Common Name:
Kerri Tetra. Also commonly referred to as the Blue Emperor Tetra, Purple Emperor Tetra, Royal Tetra, Emperor Kerri Tetra or Kerri Royal Tetra.

Scientific Name (Latin):
Inpaichthys kerri

Maximum Size:
Around 3–4 cm in captivity, making it a small and manageable shoaling tetra.

Water Type:
Freshwater

Origin / Natural Habitat:
Native to South America, specifically Brazil, where it is recorded from the Aripuanã River in the upper Madeira River basin, Mato Grosso. In the wild, it is associated with tropical freshwater habitats, and in aquariums it does especially well in planted setups with cover, subdued lighting and stable water quality.

Water Parameters:
Temperature: 24–27°C
pH Range: 6.0–8.0
Hardness: soft to moderately hard water, around 5–12 dH

Temperament:
Peaceful and social. Males may display to each other and show light chasing behaviour, but this is usually harmless when they are kept in a proper group with enough space. It should not be kept with aggressive, predatory or very boisterous fish.

Diet:
Omnivorous micro-feeder. It should be offered a varied diet including quality fine flake, micro pellets, crushed granules, frozen daphnia, cyclops, baby brineshrimp, bloodworm and occasional small live foods. A varied diet helps bring out stronger blue-purple colour and keeps the group in good condition.

Minimum Tank Size:
A practical recommendation is at least 60 litres for a small group, with a 60 cm aquarium or larger preferred for better swimming space and natural group behaviour.

Behaviour & Activity:
This is an active mid-water shoaling fish that should be kept in a group of at least 6, ideally 8–10 or more. Males are usually more colourful and may display to each other with stronger blue or purple tones, while females often show a red-orange adipose fin. Kerri Tetras look best in mature planted aquariums with darker substrate, driftwood, floating plants and open swimming space.

Aquarium Category:
Community Fish
This species is well suited to peaceful community aquariums with other small, calm fish. Suitable tank mates include other peaceful tetras, rasboras, pencilfish, dwarf Corydoras, Otocinclus, small plecos, peaceful dwarf cichlids and small gouramis. Avoid large predators, aggressive cichlids, persistent fin nippers and very timid fish that may be stressed by active shoaling behaviour.

Special Requirements or Care Notes:
Best kept in a mature, well-filtered aquarium with stable water quality and regular maintenance. It is adaptable compared with some delicate tetras, but still benefits from soft to moderately hard water, plant cover and low-stress tank mates. A darker background and subdued lighting can help intensify the blue-purple sheen. This species should not be confused with the true Emperor Tetra, Nematobrycon palmeri, which is a different species.

Suitable for:
Beginner to intermediate fishkeepers

Availability:
Common / occasional in trade, with captive-bred strains such as “Super Blue” also seen occasionally

All images are a visual representation of the fish you will receive, made to be as accurate as possible. Please note that Mother Nature is a wonderful thing, and variation in patterns and colours will occur — that is part of the unique beauty of these animals.