As others have mentioned, it is likely feeding them the wrong type of food or feeding too much.
Cichlids will always appear hungry when in fact they are not which is dangerous as we tend to overfeed them. Their diet would be mainly good quality cichlid pellets, New Life Spectrum, supplemented with Brine shrimp, lettuce, peas (de-shelled), carrots (lightly cooked to soften them) and zucchini (they love and it is good for them).
You need to keep a very close eye on the fish if it is Bloat, full blown Bloat is 99% fatal to most cichlids unless it is treated very quickly. Give them a bit of Spirulina and feed them carrots, it will help.
You sometimes have to remove the bloated fish to a separate tank to fully treat them.