Brachyrhaphis rhabdophora

Common Name: Olomina
Latin Name: Brachyrhaphis rhabdophora
Origin: Central America
Temperature: 72-82º F
Ease Of Keeping: Easy
Aggressivness: Mildly aggressive
Lighting: Any
Adult Size: 1.5-2.5″
Minimum Tank Size: 10 Gallon
Feeding: Pretty much anything, but especially appreciates live insects.
Spawning Method: It is a fairly prolific livebearer, breeding is not difficult.

Comments: Brachyrhaphis rhabdophora, along with many other small livebearers both in and out of the genera Brachyrhaphis is known by the common name Olomina. This word is a bit difficult to translate (it is Spanish in origin) but probably means something like the english minnow, describing a small fish that’s identity is deemed unimportant. It is also the napme used for guppy. That they are all enclosed in the same common name is understandable considering their relative uselessness in commercial terms. They are too small to be used as a food fish, have yet to become popular in the aquarium trade, and all have a similar body shape and coloration.

Despite not being very commercially important they still draw the interest of various educational institutions and the occasional hobbyist. In particular they are of interest in the areas of genetics and evolutionary studies. Partly this is because despite the somewhat complicated waterways that are their home in Costa Rica and the surrounding areas. Some studies often compare the behavior of two populations that occur in relatively close proximity to each other, but separated by a mountain or some other isolating phenomenon.

Overall rhabdophora is an easy fish to care for. They are hardy livebearers, with the females growing to over two inches in good conditions, while the males seem to max out at around one and a half inches. The females have a red and black arc on their anal fins, light bars on the back half of their body, and red and black stripes on their dorsal fins. Though they look similar to Brachyrhaphis roseni, they lack the iridescent band on their caudal fin, and their dorsal is not quite as brightly colored.

They generally seem to give birth to broods of between ten and twenty young, and though they likely eat some of them, are either incapable or unwilling to eat all of a brood, even in a small holding tank. They are good eaters, active tank residents, and adapt quickly to eating prepared commercial foods. Their young do well on a diet of baby brine shrimp, commercial fry foods, and crushed flake.