Scientific Name: Melanotaenia boesemani

Breeding Method: Plant chooser

Ease of Breeding: Moderate

Introduction: These eye-catching fish are one of the most popular rainbowfish in the trade. They grow to about 5 inches in length. Males sometimes get territorial and "pos­ture" with one another, flaring their fins as their colors get dark as ink. However, they rarely injure one another during such standoffs. Boeseman's rainbowfish like to shoal, and while they can be spawned in pairs, they will be happier spawning in small groups. Sex Differences: Hard to sex as juveniles. When mature, the front half of a male's body is an iridescent gray blue, while the back half is an orangey gold. Females are silvery gray with hints of gold, and their bodies are more elongated than those of males.

Water Conditions: Hardness and pH are not critical, but these fish are sensitive to buildups of metabolic waste in their water, so do regular partial changes. Temperature should be 75° to 79°F. The pH of water can affect the male-female ratio of fry, with alka­line water producing more females and acidic water producing more males. Equipment: These fish like a lot of swimming room, so give them a spacious tank-a 30-gallon long would be the minimum, but larger is even better. Locate it where it will get some morning sun, and add spawning mops, heater, and a sponge filter. Make sure the tank is covered, as these fish love to jump.

Conditioning and Triggers: Condition a group of three males and two or more females for a week or more on brine shrimp, grindal worms, daphnia, and other live foods. Morning sunlight often seems to trig­ger spawning.

Spawning: Place the fish into the breeding tank in the evening; courting will likely com­mence by morning. A male will dance and shimmy in front of his chosen partner, flashing his "courting stripe"-a strip of color that runs from his nose to his dorsal fin-as if it were a neon sign. When the female is recep­tive, they will dive side by side into a spawning mop, swimming from the bottom to the top as they lay semi-adhesive eggs along its strands. Remove the parents after spawn­ing to prevent them from eating the eggs.

Brood Size: Up to 200.

Fry Care: The egg-laden mops can be left as is, or removed to an otherwise bare rear­ing tank equipped with a sponge filter. Many breeders recommend picking the eggs off the mop with your fingers and spreading them on the bottom of the rearing tank so they will get the maximum aeration; some recommend adding an airstone for the same rea­son.

The eggs begin to hatch in roughly a week, and fry become free swimming a few days after that. They are extremely tiny and should be fed infusoria, liquid fry food, and/or green water. Add baby brine shrimp as they grow. Wring the sponge filter out regularly in lukewarm water and keep it set to the gentlest of bubbles so fry will not tire from fighting the current.

Rainbowfish fry are as sensitive as adults to water quality, so it is important to do small partial water changes every second or third day and not to overstock - a liter of water per fry is about right.

Species with Similar Breeding Habits: Red Irian Rainbow (Glossolepis incisus) as well as other species in the genus Glossolepis; other species in the genus Melanotaenia.