Among the 3 fish you mentioned, the smallest among them is probably the Convict. I believe they only get up to 6" max. You could probably do 2 in a 55 gallon. Just make sure you don't get a male-female because once they start breeding, they get even more aggressive and your whole tank would be their territory. If you decide to get a Salvini, I would say just stick to 1. They can get up to 9" (Someone correct me if I'm wrong please). They do have a beautiful color pattern though. For Firemouth, you can probably get 2 as well since they don't get much bigger than a Convict. I believe they're also the least aggressive among all the fish that you mentioned. But of course, individual traits are hard to predict with any cichlids.
For dither fish, I personally like SDs. They compliment the colorfulness of cichlids with their silver body. Also quite active but very skittish especially when young. They are schooling fish though so you would have to get at least 3. The more the better since they get more confident by the number. But for a 55 gallon, I wouldn't do more than 5. They can get up to 5-6" and take up space.
For a bottom feeder, can I ask why you want one? I don't mean to be nosy but if your purpose is to have a 'cleaning crew' then I would advise against getting one. Any fish you add would just increase your bioload, thus it's not helping with your water maintenance. But if you want to add one because you like it, then I would go with a Striped Raphael catfish. Not even my Convicts mess with my Raphael because of his armored and spiny body. But you have to exercise caution when using a net to capture one though. They can get tangled in it and can draw blood if you prick your finger on their spines. Other types of catfish that you can put are Featherfin and Pictus. They all don't get bigger than maybe 8-9".
If you're getting a 75 or 90 gallon, I would definitely say get an Oscar lol. Sorry, I'm pretty biased about that because my very first fish is an Oscar and I totally love his personality. They're like water dogs and generally very friendly with their owners. They get pretty big and are very messy fish though. So a good filtration is a must for any Oscar tank. Max size they can reach is reportedly 16" but average, I would say they get around 12-14". The same dither and bottom feeder fish can apply to this just as I've mentioned before.
Good luck with whatever you decide on!
For dither fish, I personally like SDs. They compliment the colorfulness of cichlids with their silver body. Also quite active but very skittish especially when young. They are schooling fish though so you would have to get at least 3. The more the better since they get more confident by the number. But for a 55 gallon, I wouldn't do more than 5. They can get up to 5-6" and take up space.
For a bottom feeder, can I ask why you want one? I don't mean to be nosy but if your purpose is to have a 'cleaning crew' then I would advise against getting one. Any fish you add would just increase your bioload, thus it's not helping with your water maintenance. But if you want to add one because you like it, then I would go with a Striped Raphael catfish. Not even my Convicts mess with my Raphael because of his armored and spiny body. But you have to exercise caution when using a net to capture one though. They can get tangled in it and can draw blood if you prick your finger on their spines. Other types of catfish that you can put are Featherfin and Pictus. They all don't get bigger than maybe 8-9".
If you're getting a 75 or 90 gallon, I would definitely say get an Oscar lol. Sorry, I'm pretty biased about that because my very first fish is an Oscar and I totally love his personality. They're like water dogs and generally very friendly with their owners. They get pretty big and are very messy fish though. So a good filtration is a must for any Oscar tank. Max size they can reach is reportedly 16" but average, I would say they get around 12-14". The same dither and bottom feeder fish can apply to this just as I've mentioned before.
Good luck with whatever you decide on!
