I'm a little afraid of him, if truth be told. My fish's name is Fatty McSquishy. He once was a teeny little comet gold fish (you know, the kind you can get at the pet store for 29 cents?) and now he has morphed into a rather beefy comet gold fish. He is adorable. But, he is a psychopathic serial killer.

He has had eight tank mates throughout his life. They are as follows:
Mrs. McSquishy - Another comet goldfish.
Harold - A Very fat and Orange fancy fantail goldfish.
Maude - A beautiful white and red spotted fancy fantail goldfish.
Julio- A snail.
Jacques - Another snail.
Francoise - Another another snail.
Sergei - Another another another snail.

While Julio, Jacques, Francoise, and Sergei all died of natural snail related death causes(aka eating a bunch of goldfish crap and being poisoned to death because it's so toxic) I am 99.99% certain that MqSquishy knocked off all of his fishy-roommates.

The first clue - They all died in exactly the same way. And it wasn't a typical fishy way to die. It was as if they were paralyzed from half way down their spines. They would float sideways and attempt to swim around. Eventually, exhausted, they would give up and eventually get sucked up against the filter intake valve. Eventually they would die and float down to the bottom of the tank with their mouths wide open in an expression of shock. This process took about 12 hours.

The Second clue - McSquishy is a very fast fishy. He can dart around faster than you can imagine. It's almost as if he is a ninja fish and he just warps to the other side of the tank. The other fish could never keep up with him. They were all rather fat and slow.

The Third clue - He is very aggressive for a goldfish. Normally they are very social fish and, while they are known to kill each other, they don't do it very often. But he is not afraid to lay the smack down on the other residents of his tank if they get in his way. This behavior is particularly prominent at meal times. I have seen him push his fellows out of the way, quite forcefully, to get to the food first.

My theory is that McSquishy, in a food-induced rage, would speed at his late tank mates and ram them until they were incapacitated. The other fish, being both fat and slow, could not get out of the way fast enough. They would then proceed to die in slow agony while McSquishy circled the tank, happy as a fat kid in a candy store.

The conclusion of this story?
Well since I have a homicidal maniac of a fish I can't get any new ones cause he'll just snuff out their lights so now I have a huge 15 gallon tank with one rather small, but beefy, fish in it.

It looks really sad.