Help Debunking Cichlid Advice

[dsm7]

I have a tank with some juvenile South/Central American cichlids, rainbowfish, and barbs.

Until recently, there was minimal tank aggression, as the “tank boss” (my firemouth) was relatively unrivaled. Now, my rainbow cichlid has caught up in size, so the firemouth is apparently feeling threatened and is going at the rainbow cichlid every chance he gets.

I’ve had pretty good success with not keeping more than one of the same type of cichlids together so that there’s less risk chance of a male getting protective of a female or two males of the same species feeling the need to go head to head.

I’m going to move the cichlids into a slightly larger, as well as much longer and shorter, tank, in order to give everyone more room to spread out. I’ve also read mixed opinions on stocking the tank. Has it been anyone’s experience that more South/Central American cichlids keep each other too distracted to focus in on beating up on a single fish, or does that generally make things worse?

 

[itiwhetu]

The easiest way is to divide your tank into rooms. Across the tank put large rocks or pieces of wood to define territories. Make sure you leave these alone, if a fish moves one leave it where the fish moves it to. The Cichlids recognize these as boundary lines.

 

[jaylach]

Another possible issue is mixing South and Latin American cichlids. While there is a cross over between these regions it depends on the fish. By nature South American cichlids want much softer water than Latin Americans.

An important question is the size of the tank. These fish are predators and territorial. They MUST have room to establish their own areas.

I can't say that I know your specific fish but hope that you have a large tank. You can also 'force' separation by using 1/8 inch plexiglass with a bunch of drilled holes to allow water flow between tank sections. Use suction cup mounts to place the plexiglass in the tank to, more or less, turn the tank into an apartment building with the plexiglass being the division between apartments. This worked decently way back when in 1987 when a doctor friend I knew had a 400 gallon tank with a leopard shark. He could put nothing else, including grouper, in the tank without the shark killing. I suggested this form of isolation and it worked. The shark beat its head against the wall for awhile but it didn't take long for it to learn better. Keep in mind that this solution only isolates the fish from each other. It does nothing for the possible difference in desired water conditions.

 

[Colin_T]

the more central/ South American cichlids you have in a tank, the more aggression.

 

[GaryE]

The wild territory of a nice little western African Pelvicachromis pulcher, a 'kribensis' can be 9 square metres. If you consider that against our attempts to manage aggression in our relatively tiny 3 or 6 foot tanks, it's easy to see why our fish are stressed.
I wish aquarists would stop thinking that fish are fish. They are very different creatures, species by species. Cichlidae is a huge and diverse group. In Central America, when I've watched them, they defend small areas larger than any aquarium I've ever owned against all other Cichlids. As I've gained ezperience with the group (I have only 15 years and about that many CA species bred, although I have kept Cichlids from other regions far far longer) I've decided that if I go that route again, it's one species, one tank. Looking into a tank and seeing a permanently simmering border war no longer interests me.
You can't apply the lessons learned keeping one group of East African Cichlids from one lake on a vast continent to all Cichlids. When I see people posting Cichlid advice as if all Cichlids were mbuna, I know that a torrent of bad advice is coming. It's a shame, but it's a very common over-confident beginner's error.
The fish wants to have a secure place to raise its young in. It needs to hold a territory, or in its wild wiring, it will die. When a fish in a CA community weakens with age or is ill, it is killed by its tankmates. It may be direct murder, or more commonly, harassment and murder by 'applied stress'. Sometimes, by sheer luck, people get mild individuals, and those lucky souls will say I am full of mulm.

the more central/ South American cichlids you have in a tank, the more aggression.

But that quote is absolutely true. More aggression, and as each target shows weakness, fewer fish in the tank...