First option: Go for six angels (my experience with angels is that they're best in a mated pair or as a shoal of 6 or more). Skip the firemouth (it can get a little aggressive and will probably conflict with the apistos) and add a festivum or two. The serpae tetras will likely nip at the angel's fins (even as a school), so replace with something less nippy. If the red color is a must have, I'd suggest flame tetras and I'd up the number to 8 to 10. With this stocking list, you could easily go up to 15 or 16. There are other tetras that would do fine as well if you're not attached to the red. The cories are fine. Final stocking list: 6 angels, 1 festivum, one pair of any apistogramma species, 12 flame tetras and 10 emerald cories.
Second option: You could go with a 3 or 4 more mid-sized cichlids to the list for a total of 5-7, depending on size. I'd suggest a convict or one of the Archocentrus, Amatitlania or Cryptoheros species, a rainbow cichlid, a nicaragua cichlid, or a salvini in that mix, just off the top of my head. I'd really suggest only one of each cichlid species, as there's going to be hell to pay if you add two and end up with a pair. I've found cories to be hit or miss with Central American cichlids. I wouldn't do it. Maybe substitute with a small group of bristlemouth plecos or other mid-sized pleco species. Final stocking list: 1 female jack dempsey, 1 firemouth cichlid, 1 convict-cichlid like species (as described above), 1 rainbow cichlid, maybe a Nicaragua cichlid, and/or a salvini, to reach a total of 5-7 cichlids and some plecos.
The last one is tough. By African leaf fish, I'm assuming you're talking about Ctenopoma acutirostre, which would be fine. I wouldn't put any bichir in a four foot tank except maybe Polypterus polli , which is supposed to only get to 14" or so, but I know there are folks who'd disagree and say a senegal was fine in a 4' tank. If you keep the senegal bichir , I'd stop right there in anticipation of the ultimate size and waste load. If you drop it, I can think of three species of catfish that would do well in a small group: Synodontis polli, Synodontis petricola , and the true upside down catfish, Synodontis nigriventris . The problem with the last is other species that get much larger are often sold as upside-down catfish, so you really have to make sure you're getting the right species. The leaf fish wouldn't be tempted to take a shot at eating cichlids over 2.5"-3" or larger, so a pair of mid-sized cichlids a kribensis would work. You could up the tetras to 8-10. The butterfly fish are okay, though IMO they are one of the most boring fish I've ever owned. So the final stocking would look like this: 1 leaf fish, 5-6 catfish, 1pair of a cichlid species of 3-5", 2 or 3 butterflyfish, and 8-10 congo tetras.
All these options assume that you have a filtration rate of at least five times the volume of your tank per hour. Hope this helps,
WYite
