About Christy Expertise I can answer some questions regarding freshwater fish ranging from their care to diagnosing common diseases or problems with the fish. I can also answer questions regarding the care and maintenance of an aquarium. I haven't had much luck with live plants, so can't help in that area very much. Not real good with explaining salt water or brackish set ups too well either. Also regarding goldfish, I have some comets, and have a little experience with them but mostly just general info on them. I AM NOT THAT FAMILIAR WITH ANY OF THE FANCY VARIETIES OF GOLDFISH. YOU MIGHT BE BETTER DIRECTING THOSE QUERIES TO AN EXPERT MORE FAMILIAR WITH THEM. If I can't answer or don't know something, I'll let you know, so don't be upset if I reject your question, I'll always explain why. I would just rather not answer then give an answer I'm not confident about.
Experience All personal, first hand, general fishkeeping experience. I've had fresh water aquariums now for about 7 years. I've had tropical/community fish tanks, African cichlids, South American cichlids, brackish water puffer fish, and a lot of other varieties in between.
Education/Credentials None, all personal experience
Question my mom has/had 2 gold fish in a 30 gallon tank, they are bout 4 or 5 years old, tank change happens 2 to 3 times a month one of them developed fuzzy lookin fungus something on a small part of his top fin that eventually got so big it took over most of his back it ended up about the size of a half-dollar it look like it would feel soft but meaty looking about a week ago he died we are thinking it fell off because it wasn't on him when we found him but we did not see it in the tank so we are guessing that the other fish in the tank ate it i had seen him trying to nibble on it 2 nights before he died. So i was wondering what it was & should we do something besides cleaning the tank & items in it so the other gold fish will survive? not too sure if this will help but the tank was a salt water tank a while back.
Answer Hi Tamar
Well, if the tank had been up and running with the goldies for 4 or 5 years, and was previously a salt water tank, I don't think that would be an issue. Sometimes there may be some residual salt leftover, but it would've affected them sooner if it was going to.
Sounds to me like one of two things. First, a true fungal infection is usually secondary to an injury. If the fish had an injury to the fin, the fungus could've taken over. Here's a good article on fungal infections: http://www.petsforum.com/cis-fishnet/afm/G29112.htm
Otherwise, there's a bacterial infection called columnaris, that's fairly common in fish. It is usually mistaken for a fungal infection. People will assume they are dealing with a fungus, and will buy fungus meds, but it won't help. That's because it's a bacterial infection so needs an antibiotic-I recommend Maracyn Two or tetracycline for that. Fin and tail rot is also commonly seen with this infection, which could be what happened with the fin. And, here's a good article on columnaris with photos: http://www.flippersandfins.net/Flexibacter.htm
So without knowing for sure which the fish had, at this point if the remaining goldfish isn't showing any symptoms, I wouldn't treat for anything just yet. First, don't add any new fish just yet. Wait awhile to make sure everything is ok.
One thing I do recommend, increasing the water changes. Weekly water changes and a gravel vacuum should be done, changing out about 25% of the water minimum.
Also, in case it is a true fungal infection, she can add 1 tablespoon of aquarium salt per 5 US gallons. Be sure to dissolve the salt first in a bucket with some dechlorinated water. Keep in mind, salt does not evaporate with water, it's only removed when you do water changes. So, if you take out 5 gallons of water via a water change, you'd want to add back in 1 tablespoon. Supposedly, salt can also help prevent columnaris infections, so I've read anyway. I don't necessarily agree with that, but being goldfish that salt dosage won't hurt the fish any.
Keep an eye on the fish for any symptoms. Mainly, fin/tail starting to fray or rot, any excess slime coat developing, any white stringy material, watch the mouth area for signs of redness, any red sores or ulcers all those will point to columnaris infections.
Hope that helps and good luck! Let me know if you have any more questions.
