Bedotia (Rainbowfishes)


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Rheocles (Silversides)

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General Information for Bedotiidae

The family Bedotiidae is an endemic family to Madagascar's freshwaters and includes two genera: Bedotia, consisting of the Madagascan Rainbowfishes and Rheocles, commonly known as Madagascan Silversides.

Both genera are known only from freshwaters, with little tolerence for salt. With the exception of Rheocles derhami all are native to the Eastern Versant of Madagascar. The presence of Bedotia madagascariensis in the Betsiboka river basin is the result of a 1950's translocation to the marshes near Mahitsy (Loiselle & Rodriguez, 2007).

Originally inhabiting forested streams and rivers, Bedotia can now be found in degraded and deforested areas as long as temperatures do not become extreme. Rheocles appear to be less tolerant to the loss of forest cover, and where riparian vegetation has been removed their populations have been observed to decline.

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Husbandry Information for Bedotiidae

Both genera have been kept in captivity, although Bedotia are by far the more common species currently being maintained by both the professional and hobbyist fish keeper.

Bedotia species, in general, are peaceful fish that can be maintained and reproduced in moderately size aquaria (15-45 gallons); they are undemanding in terms of water chemisty and quality, and readily take prepared foods.

In aquaria Bedotia males typically defend a small territory near available spawning sites to which they attempt to attract gravid females; in the wild, males have been observed defending a territory 5 feet in diameter and 4 feet deep.

With yarn spawning mops present, male and female will press together while swimming against or into the yarn. The female will release numerous 1mm dia. eggs, each with multiple sticky threads which aid in the eggs in adhering to the yarn. Depending on temperature, eggs typically hatch within 5 days. Bedotia eggs can be prone to fungal infections in the aquarium, and the use of Methylene Blue as an inhibitor is recommended in cases where whole clutches are lost to fungus.

Fry possess a large yolk sac and do not actively begin feeding until 3 days post hatch. First foods may include vinegar eels, microworms or newly hatched artermia nauplii; survivorship is greater with the use of small food items. Fry have proven to be delicate, and it is not recommened that they be moved via net until 1/2 inch in length; a small turkey baster or other pipette can be used to move fry while they are very young.

Rheocles alaotrensis is the only species of Rheocles to have been kept in captivity. Unlike the more forgiving Bedotia, Rheocles are very sensitive to water temperature, and a chiller is certainly required to maintain these species at their optimal health.

R. alaotrensis kept by the author survived and reproduced for two generations before physical deformities became prevalent in the population. The last generation showed no reproductive behavior and became prone to systemic bacterial infections resulting in their death. All this was despite keeping the population at 65°F and treating aggresively for infections.

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