It may strike you as strange to have to think about this, especially since gold fish in general seem to be very docile creatures; completely harmless, even to each other. In fact, you can’t even begin to imagine how one gold fish could harm another, even if they are stuck in the same tank all day long.
Truth is, you have a point. Gold fish aren’t like most people and animals; they don’t show hostility toward each other, nor are they very territorial. So why the need to keep the nature’s most fundamental law in mind when caring for gold fish?
Here’s why: gold fish don’t need to feel any malice toward their brethren to do them harm. All they have to do is look out for themselves. Don’t believe me? Observe the activity in your tank come feeding time.
Notice how each of them goes straight for the gold fish food, without taking heed of the others in the tank. None of them cares if every flake of the gold fish food is gone before everyone in the tank gets a taste; what’s important is that they have their fill. It’s no different anywhere else, be it the pet store or the pond in the park.
Survival of the fittest applies in caring for gold fish, most especially when taking care of multiple varieties at once. There is simply no way each of those types will get as much nourishment as every other if they’re all in the same tank. Keep in mind that gold fish differ not only in shape and color, but also in size and speed.
And if the only thing they all have in common come feeding time is an overwhelming desire to feast, chaos is bound to ensue. The fastest of the group are sure to eat more than they’re supposed to, while the stragglers are unlikely to get enough to last them until their next meal.
In the end, you’ll have yourself a tank of overfed and underfed gold fish, all relatively unhealthy, some probably on the verge of dying, and others already dead. Even if all fish manage to survive this cutthroat environment in the long run, you can bet they’ve suffered from several repercussions like stunted growth, ruptured intestines, and so on. All because you didn’t keep them apart to ensure none of them falls victim to the law of survival of the fittest.
It’d do you good to remember that though caring for gold fish may be a domestic hobby, it’s not free from the influence of nature’s primal law.