A fish that spends an appreciable amount of time rubbing against plant stems and other solid objects, or "scratching" himself along the sandy bottom of the aquarium. probably has an itch caused by one of several forms of parasites. (See Drawing 37.)

This ailment seldom occurs in an outdoor pool. Give all the fish in the aquarium the salt treatment, give the affected fish the progressive salt treatment, clean the aquarium thoroughly, and disinfect the aquatic plants before refilling the aquarium with fresh water.

These are more of an annoyance than a danger to larger fish, but leeches can kill small fry. The white aquatic leech, about 1/2 inch long and slender, attaches itself to the bodies and gills of goldfish.

Give all affected fish the progressive salt-water treatment. Scrub the aquarium, disinfect it with a solution of 1 teaspoon of ammonia for every 5 gallons of water, and disinfect aquatic plants in the same solution.

Fish lice are flat, transparent, and about the size of a pinhead. If enough attach themselves to the body they can be fatal. Fish with lice will rub vigorously against any solid object they can find. The parasite's blood-sucking, much like that of a mosquito’s, creates a red spot on the fish.

Treat the whole aquarium or the whole pool with potassium permanganate when lice are detected-the aquarium with 1/8 grain to the gallon, the pool at twice that strength. Two or three treatments, ten days apart, are necessary.

This is a parasitic fungus present in almost all aquarium or pool water, but one which healthy fish easily resist. A run-down fish overcome by the fungus is marked by a white scum which appears first on tail and fins, and then spreads to the body. When it enters the gills, it kills the fish. Often goldfish die before the fungus gets to the gills.

White fungus is very contagious, for when a fish is overcome by it the pool or aquarium is soon filled with fungoid bacteria.

Remove all affected fish immediately and subject them to the saltwater treatment.

Insect and Other Enemies

Dragon flies hovering over the water, darting here and there in the sun as they run down and eat tiny insects on the wing, add a touch of beauty to a pool. They are harmless, in themselves, but their larvae are vicious enemies of goldfish, particularly the small ones. They are equipped with a terribly efficient combination. First, they move by the expulsion of water from the rear ends of their bodies, which gives them lightning-fast, jetlike maneuverability. Secondly, they have sharp, pincer1ike mandibles which kill quickly.

As with most insect pests, there is not much that can be done except to kill them-both adults and larvae-on sight.