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Hello, Today I got a new friend for my fan tail goldfish as her tank mate passed away quite a while ago.
When I put her in the tank she was fine with the old fan tail no problems at all, but today as I introduced the new "friend" she wont stop chasing him and trying to bump him on the gravel... what shall i do? Is this normal???
I have separated them for now as it looked like it was really bothering the new arrival.
HELPPPP!

How big is your tank? Goldfish arn't typically agressive fish....

Inky

Its around 30l, in the same tank as it was when I had the other fantail.
I have put her into another tank with a bigger standard goldfish to give the baby a chance to calm down and she is carrying on with the same behaviour to that one too!! Has she just got an attitude problem??
When she catches up to the other fish she starts sucking on it too

Any help would be great... shes not trying to just get fruity with another fish after being alone for so long?? lol

30 Liters is way to small for a goldfish. The minimum tank size that they need is 208 Liters (55 gal) since they are in a smaller tank that is the main cause of the aggression. Goldfish are actually pretty big fish, the common/comets reaching a good 12in each, the fancy ones (fan tails, moors, ect.) reaching 8 in.

Inky

Although goldfish arent typically aggressive , I certainly have seen some that are highly aggressive particularly with the opposite sex. This is presumably down to frustration at the lack of a successful courtship in a lot of cases, and the female can be harrassed literally to the point of death. Your case however, sounds like literal aggression, the sucking is probably biting , and goldfish can and do fin-nip each other into disability or death. This often happens when a "normal-bodied" goldfish is housed with a "fancy" goldfish. The normals are often more aggressive than the fancies, and something about the fancies sets them off on a regime of persecution, sometimes ending in the death of the fancy goldfish.It is certainly not unheard of for fish to persecute the sick, deformed and severely injured, its a natural response in many animals, it is a behaviour brought about by evolutionary advantage. If you live in a shoal sometimes kicking out the sick members can be advantageous. The goldfish doesnt know that any given abnormality is contagious or not, and some dont take the risk.Its possible that a fancy goldfish could be percieved as "sick" by a more normal bodied specimen.Its only a fish, its not a bio-chemist, so its a bit much to expect them to accept all deformity.All it ever knows is that something looks wrong, or smells wrong, or is coloured wrong, or swims funny, and that can be enough to set a paranoid fish off! Fish arent truly self-aware in the way that we understand the term, so this strong instinct could be triggered in a fish that actually has exactly the same inbred deformity as the fish its persecuting, although to be fair you have a better chance of avoiding aggression by housing fancies with fancies, purely because they are all ill-equipped for battle, and a good number of them have severely compromised vision.

Those fish with large veiltails and compromised swimming ability are especially vulnerable, since they cant get away, or express via body language a lot of the swimming patterns associated with placidity and/or suboordinate behaviour that most fish take for granted in shoal situations.This means they are seen to never "back down" quite literally because they cant, and they are continually attacked because of this. Some fish with bubble-eyes like fancies and moors, often cannot see a thing, and cant always tell when they are about to get mugged, or take action in time to avoid it.

Sometimes bigger fish act aggressively in small spaces, ironically, just as often as overcrowding a tank sometimes prevents territory and aggression. This violence could quite simply be a goldfish's personal space limit being enforced. A lot of fish, once kept on their own are reluctant to share space again. They can often be placid with a fish they are raised with all their lives, and if that fish is replaced they accept no other cagemate and go on a killing spree. I once had a 1.5 inch comet beat the hell out of a veiltail 6 times its size, so you never can tell the likely victor.

Maybe a tank 5 times the size would end this problem, but in all honesty you will probably have to seperate the fish permanently, and before one of them is seriously injured or dies from exhaustion. When goldfish dont get on for whatever reason, they REALLY dont get on. Thankfully its fairly rare. People often forget that fish are individuals, and unless the fish has absolutely "dyed-in-the-wool" shoaling behaviour, there is always a chance it can be aggressive.With goldfish, never assume their rather unimpressive jaws and dentition dont cause enough damage to kill. Ive known goldies to eat large snails, other small fish, and rip each others fins to shreds, besides which, they only have to tire their opponent to kill them.Where theres a will theres a way, and in the confines of a cage they literally cant miss. They could be fighting literally all day while your out, even if they stop when you come back from work. Fish are often naughtier when unobserved lol.

Thanks for that information I always think of my fish as individuals and name them, I just couldnt help but think that Ruby (my original fantail) has just got an attitude problem!! and just being a real jerk lol
I put her in with a relatives standard goldfish who is bigger than her thinking he would sort her out but she was doing the same to him yesterday... So I was getting prepared to have to take the new lil guy back to the fish shop, but today they seem to be getting on ok.
Im going to give it until Friday and give it a go reintroducing her to the baby and if it all kicks off again ill just have to get him out of there and find him a new home, I wouldnt risk leaving them in there together to settle down, he is too small.
Is that the best thing to do? I dont think they will become friends after a few hours will they? Do you think that maybe Ruby having some time with another fish after being alone for so long would be getting her used to the idea of sharing her tank again?
He is so cute though I hate to give him back
Wow I never realised that a goldfish could really do that much damage by biting, I know when the ones in my pond start trying to get it on they can be really hard on the girls and we have had a few batterd fish from that but never realsied that the smaller tank mates can be just as bad!!
I guess I just took it for granted that she would just accept him like the old fantail accepted her... oh well... Ill see how things go until Friday.. fingers crossed.

Its possible she might get used to the idea of a cagemate again someday, often moving her to a different tank for a week or two to distabilise her territoriality can help. Then put the fish you want to share her tank with into the old tank first, leave it there a few weeks and then reintroduce her, having taken pains to redecorate the tank to make it feel less familiar. Sometimes it does work.If she is still aggressive after all that it might be better to leave her on her own.

YAYYYYYY good news, after moving Ruby back from the other tank she has finally taken to the new lil fish which is now going to be named Hercules!!
So good news all round!!/:'