i notice these same symptoms

How often are you losing fish?

How long has the tank been set up?

What size tank is it and what is the stock list?

Did these fish go through the cycling of the tank?

What are your water parameters?

There are alot of factors that can weigh in here, and we are going to need alot more information in order to help.

Stress can play a huge part in fish health, and there are many different things that could be going on.

Let's get the answers to the above questions and see if we can determine what is going on...

Any white stringy feces? Are they eating up until death? Any bloating or emaciation?

Kim

You're going to be really limited as to what Malawians you can put in a 3 ft tank, so since your losses consist of mostly new fish, I would bet on aggression being the problem in your tank. You can't rule out illness, though, because severe stress will cause the fish to be sick. Bloat is often a result of this.

Do you know what species you have in the tank? It's going to be very important in helping you make some decisions as to what you can keep and what you need to re-home.

If you don't know what you've got, post pics in the unidentified section and find out, or browse the profile section and id them.

New fish aren't overly welcome in an established tank with aggressive fish. Adding one at a time can be a death sentence. A 3 ft tank doesn't provide enough territories and space to be divided amongst the fish, and it can quickly turn into a blood bath.

Kim