People look at Tropical fish just like they are a decoration and not as a

real pet. For us the true fish keepers our fish can be good companion

just like dog or a cat. Tropical fish are like other species in many

aspects, and that includes the fact that they have diseases. They can

have fungus, eye problems and even tumors.Just as humans, cats or

dogs may get cancer or other types of tumors, so can tropical fish.

The main difference is that treatment in fish is nearly impossible.

Surgery is basically out of the question when it comes to tropical fish.

Tumors such as Mesothelioma or Brain tumors generally show

themselves as a lump under or on the skin of fish.  Like in humans

Mesothelioma occurs more often in males than in females and risk

increases with age, Mesothelioma, though rare in fish, has had a

number of miserable patients. In humans this disease as other

tumors can be treated but it is not the case in our hobby. Fish do

not get the appropriate treatment, maybe due to lack of suitable

Photo by: Shlomi Birs

lumps grow to enormous size that they are make swimming impossible. In such cases fish's quality of

life declines and you may have to euthanize them. One type of tumor that does have some success with

treatment is the kind that forms under the skin of the gill, causing it to remain open and some time to

bleed. The cause of this is usually a thyroid malfunction. Remove the fish to a hospital tank, and add 1

milligram of potassium iodine for every gallon of water. Improvement can be slow, and the full course of

treatment can take up to four weeks. Internal tumors can be quite advanced before the fish shows any

signs, such as a swelling of the abdomen. These cases are invariably fatal, with the rapid growth causing

the fish to lose its ability to swim or eat, at which time you should consider euthanasia.