There's something wrong with my fish?

Question

I have 4 fish, 3 Red Comets and a White Cloud Mountain Minnow.

Recently, 2 of the comets have been acting weird and i don't know what's wrong with them.

One of them darts around and then suddenly stops and floats for a while either on it's side or upside down and then goes crazy again and the other one just sits on the bottom of the tank on the stones on it's side. It isn't dead because it's mouth and gills are moving.

The mountain minnow is fine and the other comet is fine.

Before all this started happening i noticed that the tails of the two fish and the fins were deteriorating and there were white things on them so i looked it up and then tried everything i could from:

doing a full water change, using melafix, wunder tonic and white spot cure.

(this was before, there aren't white things anymore and the fins look fine)

is there anything i can do for the fish? is this normal? should i keep using any of the things i was using? any help is appreciated. =)

Answer 1

they might be old

Answer 2

The one that is darting might have parasites of the internal nature, or possible bacteria. I was reading a forum the other night and they were discussing how a fish swam really fast, bonked into few walls, and then died. They opened it up for an autopsy and there was extreme infection. I would suggest medicating the food with praziquatel or just buying the medicated food.  

Answer 3

thats how gold fish die i wana see them haha i wana get one or 2 if they eat minnows,...or i think i had one haha but it was attacking my pirahnas so i killed them:(

Answer 4

hi the minnow needs to school in groups of 6 plus

maby your goldfish has a swim bladder problem