In general, aggression is a function of tank size. Put a fish in too small a tank and bad attitude happens. Damsels have a horrid reputation, but are perfectly manageable in 100 gallons. Foxfaces have a panic reflex if confined that (considering their poison spine) can prove lethal to tankmates: they grow up and one day no different than any other day, they do a freakout. Same with tangs: can be fairly mild until their size and the tank size produce stress: then you have war.
There are, however, predators---carnivores that will, yes, prey on other species. Obviously tank size is not going to prevent this: you just have to know [read! ask!!!] not to house certain species together, or you will be providing a very expensive diet for one fish.
In short, when you set up your tank, plan on SOMEBODY (usually only one fish) reaching max size in about a year. And if you haven't looked it up (or asked) to find out what that is, you may find yourself owning a fish no store wants and a tank much too small for those behaviors.
As a rule, too, plan to add your more 'pushy' fish last. It's a skillset, to be able to introduce smaller fish into a tank with a dominant pushy fish: can be done, but depends on species and, again, tank size, available cover, and the built-in instincts of the fish being added. If you can get them through a week with everybody still alive, the big guy may forget they're newcomers.
Avoid mated pairs of anything, even clowns, unless you have room for the behavior change: a breeding pair of damsels (yes, clowns) takes, yes, twice the territory of a singleton, and will enforce that.
Pay close attention, always, to the alkalinity of your tank: this is the buffer level, what keeps the water 'nice' and non-irritating and keeps your fishes' protective slime coat in good shape, a protection against wounds, parasites, and infections. I like to keep mine at about 8.3. If you can't make it stay put, you're low in magnesium: keep that about 1350.
In general, a tank with multiple fish can have action and movement without nipped fins or the risk of them. Remember there's no fish your LFS can offer that won't likely be available for you to order, so don't worry about 'missing' your chance at a specific fish. When you're ready for it, when you know enough about the species to know you can house it properly with room to grow, then's the go-ahead. Random fish shopping and whim of the week is not the way to success. Planning and making intelligent choices will give you a really great tank, of whatever size.
There are, however, predators---carnivores that will, yes, prey on other species. Obviously tank size is not going to prevent this: you just have to know [read! ask!!!] not to house certain species together, or you will be providing a very expensive diet for one fish.
In short, when you set up your tank, plan on SOMEBODY (usually only one fish) reaching max size in about a year. And if you haven't looked it up (or asked) to find out what that is, you may find yourself owning a fish no store wants and a tank much too small for those behaviors.
As a rule, too, plan to add your more 'pushy' fish last. It's a skillset, to be able to introduce smaller fish into a tank with a dominant pushy fish: can be done, but depends on species and, again, tank size, available cover, and the built-in instincts of the fish being added. If you can get them through a week with everybody still alive, the big guy may forget they're newcomers.
Avoid mated pairs of anything, even clowns, unless you have room for the behavior change: a breeding pair of damsels (yes, clowns) takes, yes, twice the territory of a singleton, and will enforce that.
Pay close attention, always, to the alkalinity of your tank: this is the buffer level, what keeps the water 'nice' and non-irritating and keeps your fishes' protective slime coat in good shape, a protection against wounds, parasites, and infections. I like to keep mine at about 8.3. If you can't make it stay put, you're low in magnesium: keep that about 1350.
In general, a tank with multiple fish can have action and movement without nipped fins or the risk of them. Remember there's no fish your LFS can offer that won't likely be available for you to order, so don't worry about 'missing' your chance at a specific fish. When you're ready for it, when you know enough about the species to know you can house it properly with room to grow, then's the go-ahead. Random fish shopping and whim of the week is not the way to success. Planning and making intelligent choices will give you a really great tank, of whatever size.
