Why are the fish in my tank attacking 1 fish?

this is my first fish tank and i have had it for about a month. i looked at my tank this morning and i saw that the 3 largest fish were all chasing after the smallest they have their heads in its tail and are pinning it down to the ground.
i have 7 goldfish and 4 of them have fins of their backs and the other 3 dont (the 3 without havnt got as big as the others). all the fish have what looks like 2 tails.(a regular fish like a trout has the thin tail part at the back well these fish have 2 which made me want them) they are cold water fish.

anyway out of the 4 fish that have fins on their backs there is 1 who doesnt seem to be getting any bigger (called scooter) im not sure if its because its female or what but today i saw that the biggest white fish is chasing after it all the time (head is in scooters tail) and now there are 2 others that are also chasing it and its really bad when scooter gets stuck in a corner and they all attack it. is it because scooter is the smallest or female?

i took scooter out for a while and hope the others forgot about him but i put him back in and they still attack him. how can i stop it? i want to keep him because he my favourite

You have 7 goldies, therefore I hope you have a tank of about 250 litres or so,, because that's the size you should have for that many, if not then it may be territorial squabbling brought on by lack of space.

Alternatively it may be a little bit unwell, sick fish often get picked on, it may be worth trying to separate it for a while and see if it has any problems, if nothing else it will give the little fella a break.

Or it may not be a fella at all, and she may be preparing to lay eggs in which case they may be squabbling over who's going to be daddy and chasing her all over the tank.

hmmm it happens you might wanna get rid of the fish because it may end up being killed i was silly enoug to get a sucker fish and put it in my gold fish bowl and the gold fish ate it lol

How big is you're tank? The fish may be fighting for territory. The smaller fish are usually the males. For only having your tank a month, 7 fish is too many. Make sure you are testing the water for pH, ammonia, nitrates and al that stuff. Find out what kind of fish you actually have, they may not be compatable

it's a part of nature. The larger fish a showing their dominance. I have Chiclids and they do the exact same thing once they get so big. You might not have enough room for so many fish. I have a 30 some gallon tank and have 6 fish. Some say thats too many?

They are trying to mate w/ scooter. if the big fish have white soots on their heads and gill theyre in breeding season. GOOD LUCK :)

7 goldfish need an 80 gallon or larger tank. Even if the tank is that large and fully cycled you shouldn't have added 7 fish to already. The fish are fighting for dominance because they don't have enough space and are probably suffering from ammonia poisoning.

**

hi there!! i fink that fish is going to lay its eggs and the other fish know this and they want to eat the eggs!! that's why the chase her!! we have a pond full of fish and this is the time of the year they start to lay there eggs!! the babies hatch and they are black and then change to gold!! good luck wif them!!