I bought the pair about a week and a half ago from Petsmart and they were getting along fine until now.
75 gallon tank, two small orandas and two comets.
It started with the oranda. This morning, I checked on my fish like I do every morning at about 6:30 before I go to work. I noticed that Gloop, my beloved female, had a small tear in her tail fin. I decided to watch it closely in case it got worse. I work shifts on a school bus so I come home several times a day between routes. I came back and her pretty tail was covered in long tears! She doesn't seem sick at all, but I was shocked. Such a change from this morning...and then I noticed that my other oranda, Chancho, about her size, is acting like he's eating her tail.
He grabs her tail and sucks it into his mouth, then yanks like he's getting a bite to eat! He's shredded her beautiful fan tail.
He isn't the only one though..one of my tiny comets, Dipper, is doing it to. I tried isolating them in a colander for a few hours and then went back to work, came back, let them out, then they started instantly attacking poor Gloop again!
But they're the only ones doing it. My last little comet, Neil, is perfectly fine with her. He hasn't touched her.
The ammonia levels in the tank have risen a bit in the past few days and I've been doing partial treated water changes, about thirty percent.
I also changed their food from flakes to pellets the other day, because I heard that pellets were better for the orandas due to less air intake.
What could be causing this??
I moved the bad guys to a time out tank for the time being. I've also been keeping a very close eye on Neil, but like I said, he hasn't touched her.
She isn't acting sick at all, no rubbing, no weird floating, she's just as curious and active as ever and her appetite is just fine.
(P.S. Never ask Yahoo answers anything. The site gets worse every day. Only answer I got was 'rub some bacon on it'. Been getting answers like this for a considerable amount of time now. So sad because I used to get educated answers!)
75 gallon tank, two small orandas and two comets.
It started with the oranda. This morning, I checked on my fish like I do every morning at about 6:30 before I go to work. I noticed that Gloop, my beloved female, had a small tear in her tail fin. I decided to watch it closely in case it got worse. I work shifts on a school bus so I come home several times a day between routes. I came back and her pretty tail was covered in long tears! She doesn't seem sick at all, but I was shocked. Such a change from this morning...and then I noticed that my other oranda, Chancho, about her size, is acting like he's eating her tail.
He grabs her tail and sucks it into his mouth, then yanks like he's getting a bite to eat! He's shredded her beautiful fan tail.
He isn't the only one though..one of my tiny comets, Dipper, is doing it to. I tried isolating them in a colander for a few hours and then went back to work, came back, let them out, then they started instantly attacking poor Gloop again!
But they're the only ones doing it. My last little comet, Neil, is perfectly fine with her. He hasn't touched her.
The ammonia levels in the tank have risen a bit in the past few days and I've been doing partial treated water changes, about thirty percent.
I also changed their food from flakes to pellets the other day, because I heard that pellets were better for the orandas due to less air intake.
What could be causing this??
I moved the bad guys to a time out tank for the time being. I've also been keeping a very close eye on Neil, but like I said, he hasn't touched her.
She isn't acting sick at all, no rubbing, no weird floating, she's just as curious and active as ever and her appetite is just fine.
(P.S. Never ask Yahoo answers anything. The site gets worse every day. Only answer I got was 'rub some bacon on it'. Been getting answers like this for a considerable amount of time now. So sad because I used to get educated answers!)
Sorry to hear you are having this problem and getting those dumb answers too. Goldfish are known to gang up on weaker/sicker/smaller fish sometimes and once one starts the others catch on and join in. What caused the increase in ammonia? Can we see a full tank shot? Makes it easier to see what we are actually working with. 
