My fish is a horrible vicious for-no-reason killer----or not. Discussion.

[Sk8r]

There are several kinds of fish.
Predators on other fish, like the lion or ghost eel.
Predators on inverts---quite a range of these, from the copepod-eating dragonet to the coral-eating parrotfish. And shrimp-munchers galore.
Grazers on algae---who will often not mind shrimp in the diet.

If you unknowingly put a fish in with its favorite dessert, well, dessert gets had.

BUT---there's another provocation to a fish fight. Territoriality. And that includes tank size. Even a baby fish has wired into its system a certain space it needs to grow. And fish will FIGHT for more space. How does it create space? Well, by eliminating other fish IN it, is one way.

Will all fish fight? Pretty well. You'd be hard put to find a milder-mannered fish than a mandarin. Will a mandarin kill another fish? YES. If you add another mandy to its territory, especially if it's barely making a living, it will kill that fish or die trying. The lawnmower blenny is mildmannered. But will kill to preserve its territory. Chromis will kill each other at night, in fights over sleeping holes. They disappear one by one, leaving the owner sure there's a predator in the tank. Nope, just too many chromis for the available spaces. What's an 'available space?' They decide that.

The way you don't toss a puppy into a piranha pond, you read up before you add a fish, and ALWAYS look at the adult size, because that will govern the territory demand of the growing fish. Blennies, gobies, dartfish, dwarf angels, fairy wrasses are all caught and sold as adults (a convenient shipping size, because their young are way tiny). Damsels don't have too much growth potential: they top out at about 5"...but their lifestyle requires about 100 gallons or more before you can have multiples without problems. Rabbits, tangs, regular angels, larger wrasses, etc, are caught as babies (a convenient shipping size, because the adults are large) and top out usually around 8 to 10". Is this fish going to be content in a little glass box even to start with? And are you personally prepared to find a home for a 10" to 12" fish in your town? Euthanasia of a pet you've had and hand-fed for years is not a pleasant prospect. But where are you going to put an 8' long tank?

Please, please, please consider how fast these critters grow and do some visual math with your tank, and your budget. There are MANY bright, wonderful fish besides tangs and big angels: basslets---yellow, fuschia, ice blue with red; red---fairy wrasses; damsels---brilliant blues, yellows;chromis---green and ice blue; gobies---yellow, white and reds; blennies---some change pattern like a cuttlefish. The sea has a lot of alternatives. You say what color and shape you want, and I'll bet it can be had.

 

[Pigpen17]

I have always looked at it as if fish are not a pet like we think of pets. It's not like keeping cats, or dogs, or what have you. They are a whole different eco system. Keep a mixed fish population is equal to trying to keep dogs, cats, rabbits, birds, mice and lizards all in the same house. You have to pay attention to what eats or hunts what.

 

[CStrickland]

Excellent post
I would add that this is a very good reason to plan the stocking list for your whole tank in advance. It's a good way to pass the time while you are waiting for the cycle to finish, and it can get a little tricky to make sure everyone has their needs met if you are looking at competitors for a unique food like pods or fish that aren't that closely related but have body-shapes that are similar enough to trigger aggression.

If you have a plan and then add in order of least to most territorial, you can head off some aggression. Plus, just like grocery shopping, when you have a list in hand you are less tempted by impulse buys when you stop in at the lfs for salt.

Of course, it's not set in stone. You may find a new fish you like or sometimes a fish like cardinals will look awesome in a pic but when you see it in the store you realize you aren't a fan cause it just hovers in one spot. But it's still easier to edit a plan than to try and add them one at a time piecemeal.

 

[A.Astore]

Excellent post
I would add that this is a very good reason to plan the stocking list for your whole tank in advance. It's a good way to pass the time while you are waiting for the cycle to finish, and it can get a little tricky to make sure everyone has their needs met if you are looking at competitors for a unique food like pods or fish that aren't that closely related but have body-shapes that are similar enough to trigger aggression.

If you have a plan and then add in order of least to most territorial, you can head off some aggression. Plus, just like grocery shopping, when you have a list in hand you are less tempted by impulse buys when you stop in at the lfs for salt.

Of course, it's not set in stone. You may find a new fish you like or sometimes a fish like cardinals will look awesome in a pic but when you see it in the store you realize you aren't a fan cause it just hovers in one spot. But it's still easier to edit a plan than to try and add them one at a time piecemeal.

+1 !! Having a plan and researching heavily pays off!

 

[Cancun]

+1!!! Where were you a few years ago when I was starting out Sk8r! I love your posts! If we would all do research and always plan for the fishes adult size instead of their juvi size....we could save a lot of headaches down the road. And taking the large fish to my LFS as a trade in....

 

[Dombake]

would blue/green chromis be a good choice for my tank and if so, how many would be acceptable in terms of space?