 |
Symptoms:
Small fry and eggs can become victims to Hydra. The only symptoms, which are only noticeable under a low-power microscope or magnifying lens, are small, red lesions. These are the result of being stung or pricked by Hydra. Stung fry or eggs usually die from the injury.
|
 |
Cause:
Hydra. Hydra is a wonderful food source for small juvenile fish and will spontaeously grow in foul water. Hydra normally feed on small crustaceans, worms, and insects. If water conditions deteriorate in a breeding tank, or if Hydra are deliberately introduced, they can become a predator of the eggs and even small fry. Hydra are capable of reaching lengths of up to 2 cm and have a white, saclike body and a circle of up to ten long, slender tentacles around their body opening. The tentacles have special cells called nematocysts, which can either sting or stick to the prey. Hydra reproduce rapidly, either asexually by forming buds or sexually. When reproducing sexually they are usually hermaphroditic and lay a single egg.
|
 |
Treatment:
Hydra can be eliminated by several different means. Fulbendazole is an effective medication against Hydra. Treat using 1 gm for every gallon of water. If you are uneasy about medicating the tank or unable to acquire Fulbendazole, there are several alternatives. The three-spot gourami and the paradisefish will consume large numbers of Hydra. Hydra can only survive on live food, so they can be controlled by changing the diet to flake. Raising the temperature of the water to 108 F for four hours (after removing your fish) will certainly kill any Hydra. Hydra are also sensitive to salt; consequently, a 0.3 - 0.5% change in the salinity of the tank should prove effective. If none of these methods works, a careful dose of 0.5ppm Copper Sulphate will do the trick. Copper Sulphate is also toxic to fish so this treatment must be used as a last resort and used with extreme caution. Bear in mind also that some water conditioners have a high metal ion binding capacity and may render a Copper Sulphate treatment useless.
|
Diseases
Top of page