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Melanotaenia lacustris
Lake Kutubu Rainbowfish, Turquoise Rainbow Fish

 Age of Aquariums > Freshwater Fish > Turquoise Rainbowfish - Melanotaenia lacustris

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Melanotaenia_lacustris_1.jpg (15kb)
Photo Credit: Kate Claxton

Name: Melanotaenia lacustris
Size TankpHTemp
Origin: Lake Kutubu (Papua New Guinea)
10 cm 150 L 7.3 24C


These beautiful, active fish should be kept in shoals of at least 6. They are suitable for community tanks with larger fish e.g. Congo Tetras, but can become nippy as adults. A planted tank with plenty of swimming space is ideal. They can be kept with other Rainbowfish, but hybridisation may occur. They enjoy a variety of foods such as flake, live food and benefit from vegetable based foods in the diet. Rainbowfish are often overlooked as juveniles as they appear drab in the LFS, but have a fantastic range of colours when adult - hence the name 'Rainbowfish!'

I started with these rainbows in a 150L tank and would not consider keeping them in anything smaller having seen their size now. Rainbowfish become fatter bodied with pointed heads when adult and require a LOT of space. The adult size of some rainbows is often underquoted - a large tank is required for these fish to thrive. My rainbows all share a 400 L tank and the colours and movement in the tank are stunning - they are EXTREMELY greedy fish and definitely know when it's feeding time...the tank sits behind my computer and I often get the feeling of being watched...! They are bottomless pits to feed, and as a result a large shoal of rainbows produces a lot of waste. Ensure regular tank maintenance to keep the substrate clean!

Contributed by Kate Claxton

I currently have a turquoise and a boesemani rainbow in my aquarium. The two are one of the most beautiful fish I have so far kept. They are peaceful and get along with my 3 golden barbs, neon black tetra and a blue gourami. I highly encourage a fish keeper to experience the joy of these fish. They are relatively easy to maintain and like a well planted tank (real plants or plastic) with a good flowing current. I encourage an appropriate ratio of plant space to open water. They grow to 11 cm and require a tank of a least 120 L.

Contributed by Ivan Vojvodic

I have been keeping rainbowfish for many years now and they are by far my favourite fish. Lacustris are truely stunning fish when full grown, the males can change from a deep dark blue to shimmering green in the blink of an eye. They are a hardy fish, will eat almost anything and have a great personality. They are best kept in a large aquarium, 120 cm, with a high flow rate and plenty of room to swim. To see them at their best they should be kept in pairs, male and female, with other species of rainbows or in a school of 4 or more. Females are relatively drab, but they bring out the best in the males. Lacustris gets on well with nearly all other fish, mine get on really well with a rather large and grumpy rainbow shark. They make a great feature fish for any large aquarium and don't need to be fussed over.

Contributed by Renee Mewing

I bought four M. lacustris from a long-standing stock at my LFS. They fit in nicely in my 400 L tank. They occasionally schooled with my neon and phantom tetras (!), and were generally very active fish. Despite my wife's protests that they were plain white fish, within a month they had transitioned to an incredible shade of deep, iridescent blue-green, darker and prettier at night. Since this was against a white sand substrate, I figured they would look even nicer with darker sand. Today I added in some black sand during my regular water change. This was the second major change they had had...the last one, three weeks ago, was a 50% + filter cleaning, but this time I changed out all the filter media (except the biofilter), and scrubbed the brown algae from the filter tubes. The sand came last; it was a relatively coarse sand with very little dust in it. After adding the sand, the rainbows died, one by one. From what I could see, each of them began swimming erratically, then lost the ability to fight the current, then could only flop a little, then they simply died. All four of them. I have heard that some Rainbows can be sensitive...I suspect that these guys are. Noteably, my dwarf gouramis, neons, cardinal tetras, phantoms, serpae tetras, corys, otos, and my flying fox came through the whole incident with flying colors. Regardless, if I were an experienced aquarist, I'd get these fish again. They were wonderful pets, for the brief time I had them.

Contributed by Jon

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