Truethfully, the only happy fish in that tank right now are the glowfish. Common pleccos grow to be OVER a foot long! No matter how small you buy them, thye still grow up and if you don't rehome him to a petstore or a friends 75gall then he will have growth stunts and not survive over a year.
Zebra danios are to hyper and they need big spaces, they also like schools, so you would need to get more wich would overstock your tank. The african cichlid will get to bi for that tank unfortunatly....
If you like your current fish theem try switching it to this...
-2 glofish
-6 silvertip tetras (stimulate danios)
-2 otto cats (stimulate plecco)
-1 sunset dwarf gourmi (stimulate cichlid)
Your current fish are not going to be healthy, as your bioload is to high. Please consider your fish's needs and rehome or upgrade your tank. I know its hard, but you can research everything I said to double check):
I'm sorry
Erin