The Kamaka Rainbowfish
Melanotaenia kamaka
by Eric Bodrock

These are one of the newer species of Melanotaenia rainbowfish to be seen in the USA market/hobby in the past year.  At first glance the fish resembles M. lacustris, the Turquoise rainbowfish, which is more commonly seen, but there are some big differences.  The blue color of M. kamaka is mixed with a silver shine, making it much brighter.  Their overall body is also covered, for the most part, with a slight pinkish/orange cast that can be seen as the fish moves and reflects light.  The fry color up at a much younger and smaller size than the M. lacustris, showing off the bright silver/blue color as early as two months.  M. kamaka only grows to about half the size of M. lacustris, obtaining a maximum size of just three inches.

I obtained a group of adults, approximately one year old, which consisted of four females and a single male.  The adult males have a much higher body than the females and have a little bit more of an intense color to them.  Males can start to be sexed out at about four months of age at the size of one and a half inches by their color and body shape.  I must add the females do show some nice colors, more so than many other Melanotaenia species, making them just as desirable as the males.

The group was housed in a twenty-gallon high aquarium, which was filtered by a single Hydro-sponge filter.  The bottom had a couple of handfuls of crushed coral scattered about to bring the pH up to about 8.0.  Temperature was maintained steady at seventy-eight degrees Fahrenheit.  A large acrylic yarn mop (I prefer to use dark green yarn) was placed on the bottom and another floated in the aquarium.  Diet consisted of frozen bloodworms, live blackworms, live baby brine shrimp and assorted flake foods, all which were eagerly accepted.  Once to three times a day they were fed. 

Within days of setting them up, the floating mop was pulled and found to contain several tiny, clear eggs.  As the fish settled in to their home, more and more eggs were found more often.  Pretty much anytime the floating mop was checked, eggs could be found.  Notice I said “the floating mop”….. I found it rather odd that I rarely ever found an egg in the sunken mop, even if it was the only one in the tank!  To hatch the eggs, I remove the mop and place it in a one or two gallon container which is filled with water from the spawning aquarium.  I add an airstone with a gentle airflow and place the container in a darker part of the fishroom away from any direct or bright light.  It takes about ten days for the eggs to hatch and I found that a good many of them do hatch.  The problem now is feeding the tiny fry.  At hatching, the fry are just over one millimeter in total length and as thin as a hair…..if you don’t know that you’re looking for tiny fry, you’ll miss them!

First foods I offered were Euglena and “sponge scrunge” (the squeezed “dirt” from a seasoned sponge filter); in addition, I added a small piece of Java Moss, which houses an assortment of smaller “bugs” the fry may feed on.  The numbers of fry seem to increase for a few days as more eggs hatch, but soon the number of young decline as the days pass.  It takes about a week before microworms seem to be taken by the youngsters and another week for newly hatched brine shrimp.  What started out as a container of maybe a hundred and fifty fry, after ten days, will be down to a couple dozen.  From that point the fry are easy to grow out.  The last catch to them is the rate of growth……which is very, very slow!  At four months the fry will range from three quarters of an inch to one and a half inches. 

If you are a Rainbowfish fancier and don’t have these guys, I’d have to tell you that you should add them to your fishroom “wish list”.  With their attractive colors, peaceful behavior, easy maintenance and rarity, they should fit that “need” for the oddball hobbyist. 

Eric Bodrock, Aug. 2004