A gold fish has a memory span of 3 seconds (that's like having a computer with one byte of memory!) It is said that having a Heron statue by your pond will keep other herons away...unless of course, it's mating season. The Japanese consider it good luck to add at least one solid black koi to a fish collection. Crush a little vitamin C and disolve it in water, then soak your fishes food in it for 5 minutes. This will make their whites whiter (much safer to try then Clorox, which will fade all their color, not so much from the bleach but because they are dead.) You're supposed to be able to tell the boys from the girls in koi by their girth--females ar plumper, males are more streamline. So why are half my fish chasing around my skinny shusui this morning? The best way to tell is to watch them spawn. That one that's being chased all over the pond is a girl. The boys would be the mean ones chasing her.