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Care guide · Freshwater · fish

Lake Tebera rainbowfish

Melanotaenia herbertaxelrodi

Lake Tebera rainbowfish (Melanotaenia herbertaxelrodi)
© Klaus Rudloff / CC BY-SA 4.0, via Wikimedia Commons. Photo: Klaus Rudloff / Wikimedia Commons · Source · CC BY-SA 4.0Resized and compressed; no cropping or colour changes.

The Lake Tebera rainbowfish (Melanotaenia herbertaxelrodi) comes from the remote Lake Tebera basin in Papua New Guinea. It is an active, peaceful shoaling fish that needs a long aquarium with open swimming room and planted margins. Mature males are often more colourful than females. Sources disagree about the recommended aquarium pH, so stable conditions and careful acclimation matter more than chasing one exact number. Keep the fish in a group and ask the breeder about the water in which the group has been raised. When planning a shoal, also account for adult size and avoid boisterous companions that would keep the fish under constant pressure. Careful acclimation, suitable filtration and regular water changes help maintain water quality. This species is not a good choice for a small, short aquarium.

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At a glance

Temperature
20–26 °C
pH
7.0–8.0
GH
10–15 °dGH
Aquarium length
At least 120 cm
Minimum aquarium volume
At least 81 L
Adult size
Up to 9 cm
Group size
At least 6 individuals
Temperament
Peaceful

About this species

The accepted scientific name is Melanotaenia herbertaxelrodi Allen, 1981. It belongs to the family Melanotaeniidae and was named in honour of Herbert R. Axelrod. Males often have a yellow to greenish body with a dark blue-black lateral stripe; the dorsal, anal and tail fins may be red or yellow. Colour varies with individuals and condition. Seriously Fish records a maximum standard length of 9 cm. Standard length is measured to the base of the tail fin, so it is not the same as total length.

Natural habitat

The species is known from the Lake Tebera basin in the highlands of Papua New Guinea. The original description gives a clear stream several kilometres from the lake as the type locality, where 21°C and pH 7.8 were recorded. Marshy margins, vegetated lake waters and small feeder streams have also been described. These are field observations at particular sites, not a complete set of aquarium targets. Its known range is restricted. An Australian-hosted draft impact report discusses possible lake drying during El Niño events; this is context, not a confirmed trend for every local population.

Aquarium and layout

This is an active shoaling fish and a long aquarium matters. Fishkeeper recommends a tank at least 120 cm long; Seriously Fish also lists a 90 × 30 cm base and about 81 litres at 30 cm height. These are different source recommendations, and the smaller geometric volume does not guarantee enough swimming room for a shoal. Use the cautious 120 cm length guidance and keep at least six together, preferably six to eight or more when space permits. Plant the margins, leave a long open swimming lane, maintain clean water and use a secure lid.

Water conditions

Seriously Fish gives aquarium values of 20–26°C, pH 7.0–8.0 and GH 10–15 dGH. Fishkeeper gives the same temperature range but lists pH 6.0–7.5 and broader hardness tolerance. Because the pH ranges differ, we do not invent an average or a single exact optimum. Keep conditions stable, measure them reliably and ask how the fish were previously kept. Acclimate gradually and avoid abrupt changes. GH and KH are different measurements; the species sources consulted do not establish a specific KH target.

Behaviour and group size

Lake Tebera rainbowfish are peaceful and social but can be skittish. A group of at least six conspecifics is important; Seriously Fish recommends six to eight or more. They use mainly mid and upper water and need space to swim and display. We do not list individual tankmates as guaranteed matches: general compatibility lists do not prove a safe pairing with every species. For a community aquarium also consider adult size, activity, water needs and available swimming room. A field record of two species together is not, by itself, proof of aquarium compatibility.

Feeding

The species is omnivorous. Seriously Fish lists dried, frozen and live foods as accepted options; Fishkeeper also mentions flakes, green foods, micropellets and small prey. Offer a complete dry food the fish can readily eat and vary it with suitably small frozen or live foods. An existing flake product is linked as one part of a varied menu, not as an exclusive diet. Dried Daphnia is only a supplement. Give small portions that the whole shoal can take and remove leftovers to help maintain water quality.

Breeding

Lake Tebera rainbowfish scatter adhesive eggs among fine plants or a spawning mop. A separate breeding tank with a sponge filter and suitable fine material makes eggs and fry easier to monitor. Adults do not provide dependable parental care, so check the spawning material regularly and move eggs to a separate rearing tank when needed. Seriously Fish gives about pH 7.5 and 22–24°C for targeted breeding. These are source-reported spawning conditions, not a reason to change the normal aquarium abruptly. Eggs hatch in about 7–12 days according to that source, depending on temperature; tiny larvae first need very fine rearing food.

Sources & review

This care guide draws on several specialist sources and was last checked on .

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