My cichlids (malawians) are killing each other off How can I stop this

There is a war going on my tank. From 25 fish I now have 11 left.

The fighting does not stop.

Solutions to solve your problem: adequate tank size, correct sex ratio, compatible species selection, & rocky aquascape. To balance out the aggression you'll need to apply ALL of these solution techniques to your set up:

The violence in your tank is to be expected if your tank is smaller than 55gal and/or if you have an improper sex ratio. I'm assuming your lake malawi cichlids are mbuna since you didn't specify the exact species of malawians you have.

A 55gal+ is required. 75gal+ is recommended for hyperdominant species (chipokae, kenyi, auratus, etc). If you can't meet this requirement, expect the bloodbath to continue. Assuming you have a 55+ tank, you'll need 8-12 malawians minimum.

Adjust the sex ratio in your tank. Each species of mbuna requires 2-4 females per male (for example 3 male red zebras, 6-12 female red zebras). Certain species (especially the hyperdominants mentioned in the previous paragraph) won't tolerate the presence of another male of their own kind in the tank and will constantly attempt to to eliminate it.

Stock your tank with compatible aggressive types. While most african cichlids are aggressive some are more aggressive than others. The more aggresive types thrive in a high aggressive environment; while the semi-aggressive types in this same set up are disadvantaged. For a less hectic african cichlid set up, stick to the more 'peaceful' species such as yellow labs, rusties and acei. Be advised that a 'peaceful' mbuna is still more aggressive than most tropical fish.