learn a lesson here, you should never buy fish without first doing a little research its alrady cost you one fish that you paid for. for all you knew these could have been fish that need a 10ft tank....
to answer your question as no one else seems to have an answer for you.
A) a larger volume of water will give the fish more room to move and keep the stress levels low, healthy fish grow better. also the larger the water body the lower the nitrates will be. very high nitrates will stunt the fish
B) 10-15% waterchanges every other day will grow the fish on at about double the rate, be careful here too many water changes will send your tank in to a mini cycle which will in turn stress the fry (ref A) after about 3-4 months of age 30% weekly water changes will keep your fish illness free, healthy and carry on with continued growth.
C) (this is the controversial method of power feeding) lots of guys on here will tell you feed small amounts but often during the day. say 4 times a day. in my opinion all this does is achieve a fat unhealthy fish that will pollute its water sooner therefore needing more water changes. personally i would advise feeding twice a day all the fish can eat within 30 seconds. any more than that and you'll notice food left at the bottom of the tank uneaten rotting and again polluting the water and indirectly stunting your fish
D) at this age you should be feeding flake. if they are very small crush it up and put in the tank, african cichlids will suffer from a condition called bloat if you feed them meats. its the high protein that effects the fishes digestive tract causeing what i would imagine is a slow and ainful death. although this type of fish will eat insects and other fry in the wild its best advised to keep meat to a very minimum if at all. krill would be the best option, and blood worm being one of the worst.
hope these tips help
Dan