Aquaria Information from



   Common, successfully treated goldfish diseases fall into two categories: bacterial and parasitic. 

Bacterial problems 


   This disease is not limited to goldfish, and can manifest itself in several different, individual ways, or with varying combinations of symptoms. It can look like a classic case of mouth fungus, or appear as fin and/or tail rot, or look like a whitening decay on the body. 

   While any broad-spectrum antibiotic can be effective against columnaris, we have found that Neomycin works well. Nitrofurazone also brings results. Sodium sulfathiazole has been successfully used, but it doesn't cure columnaris as rapidly.

 Bacterial Hemorrhagic Septicemia: 

   Goldfish with bacterial hemorrhagic septicemia are most likely the victims of a type of aeromonas bacteria. The primary symptom is a red ulcer or lesion which can quickly deteriorate through layers of skin, tissue, and muscle. 

   Most of the broad-spectrum antibiotics can be useful in treating this disease; nalidixic acid also seems to work against this bacteria. 

Parasitic problems 

   Parasitic problems occur frequently in goldfish; the most common forms of parasites are: 

Ichthyophthirius ("Ich"): 

   "Ich" in goldfish is most frequently caused by excessive ammonia or nitrate levels or by a very low pH than by a rapid change in temperature. It is manifested by tiny spots covering the entire fish body, Ich is easily treated by malachite green or any of the popular Ich medications.


   Flukes can be detected by a variety of symptoms: pale body color, heavy breathing and/or gray lesions in the gills. Often gill flukes will open the door for columnaris as well. 

   There are two well-known, effective treatment methods for flukes. One is with Dylox, at a ratio of 250 milligrams per 10 gallons of water. Change at least three quarters of the water every other day, and redose for up to ten days. The second treatment involves putting three drops per gallon of water of a malachite/ formalin mix with 37 per cent formaldehyde in your tank. 

Anchor Worm: 

   Anchor worm is seen as a thick, whitish thread with a frayed end hanging off the goldfish. The other end is literally hooked or anchored to the fish's body. The worm should be removed with tweezers. Note: This leaves an opening that can be the source of secondary bacterial infection, and should be treated immediately, with an antibiotic. 

   Free swimming anchor worm larvae can best be destroyed with dylox. The malachite/formalin mixture described under Flukes can also be used. In addition, potassium permanganate is effective, primarily as a bath. The fish should be subsequently placed in clean water with dylox. 

Fish Lice: 

   Fish lice should be dealt with in the same manner as anchor worm, by removing the adult organism with tweezers, treating for secondary bacterial infection, then using one of the parasitic treatments. 

For all goldfish diseases, prevention is better than any cure. Clean water with plenty of oxygen, avoidance of excessive heat, the proper biological filtration (eliminating any buildup of nitrogenous waste product) and, most importantly, proper nutrition in the form of high quality goldfish food are all key elements in avoiding goldfish diseases.

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