2017—This fish is now on the “vulnerable” IUCN Red List Photo by Darrell Ullisch
A SMALL RAINBOW
Rainbows are one of my favorite groups of fishes. They are peaceful, usually easily kept, long lived, come in a wide assortment of beautiful color patterns, and are fairly easily bred. The only drawbacks I can think of are that the tiny fry are sometimes difficult to raise, and they take a fairly long time to mature. Melanotaenia eachamensis is a very colorful Austrailian rainbowfish that comes from Lake Eacham, a small crater lake Southwest of Carins in Queensland, Australia. They are a fairly small rainbow with the male reaching about 2-3 inches maximum. Females are about 2/3 the size of males. I received a group of 8 half grown fish (6 males and 2 females) that showed a little color, but nothing outstanding. As they have matured and grown accustomed to their surroundings, the males have become strikingly colored. About 10 alternating horizontal lines of red and iridescent blue cover the entire body. The fins are fully colored also with red and blue spotting within a black lacy pattern and a white to yellow background. The final accent is the black edging along the entire length of the anal and dorsal fins. Both sexes have large, iridescent blue eyes. These are truly beautiful fish.
This rainbow will eat a variety of foods, including live, frozen and dry flake. I like to include some spirulina flake for vegetable matter. They stay near and feed off the surface and usually do not pick up food from the bottom. I would keep them covered as they could be jumpers, especially since they are somewhat shy and spook easily. Live plant cover seems to make them more comfortable and color up better. They are a friendly schooling fish that likes temperatures around 24-30 degrees Centigrade. Harder water seems to be best as I kept mine in tap water with dolomite gravel. Baensch Atlas 2 has this fish pictured on page 1120, but it only shows a rather drab female and mentioned that breeding was unknown (at the time of publication).
Breeding was fairly similar to most rainbows. I like to use dark green yarn mops to collect the eggs in. The very dark color helps me see the eggs better for picking and I feel the fish prefer to lay their eggs in a dark mop. Females will begin laying eggs at about 1 to 1¼ inches. Most days at least a few eggs will appear in the mop. On some days larger numbers are laid and that usually coincides with a storm approaching (barometric low) or a water change. Their eggs are extremely tiny, about ½ mm in diameter. I squeeze most of the water out of the mop and hold it up to the light as I search through it for the tiny clear beads. They are slightly adhesive so I need to roll them in my fingers before they will drop off in the water of the hatching pan. They are quite hard and not delicate. City tap water with a few drops of methylene blue has worked well in hatching them out in about 7 days under light areation. Later I tried hatching their eggs in water with no methylene blue, but added daphnia to keep down the fungus and bacteria from infecting the eggs. This worked just as well if not better, as the hatched fry seemed to be more vigorous that way and the daphnia did no harm to the eggs or fry. I think that this would be a good way to hatch the eggs of many other species of fish, especially if they were sensitive to methylene blue.
FRY A CHALLENGE
Raising the very tiny fry was the main challenge with this species. A flashlight and eyedropper helped me find and remove the newly hatched fry to a larger aquarium. These fry can hardly be seen! They swim very close to the surface looking for infusoria and tiny food particles. APR, Liquifry, or other very fine food must be fed for over 2 weeks before they will take newly hatched brine shrimp. Maintaining clear unpolluted water is a challenge when feeding. I use snails and daphnia in with the fry to help clean up the excess food and pollution. Once the fry are on brine shrimp, raising them is much easier. Growth is fairly slow but steady, and they can reach over 1 inch in 4 months, showing signs of sexual differences at that time.
In summary, Melanotaenia eachamensis is a beautiful, peaceful, and easily kept rainbowfish that offers a little more challenge to breed and raise. It is from those challenges that we learn the most to improve our fishkeeping skills!