Yeah, I loved goldfish. I had a 60 gallon tank with about 8 that survived "the learning curve" They are dirty, they like to eat and poop a LOT. I found out that goldfish really do thrive in cooler to cold temps and a LOT of oxygen. If you live in a warm place and want to keep them inside you need to have the air at 70 degrees or a refrigeration unit like in some saltwater set ups.
I had 2 large Fluval canisters, 2 of those large wheelie filters . I had a large sm pond sized UV sterilizers to keep things clean. I did 10-20 % water changes weekly, matched the temp etc. Oh and I had one of those large sand tower filters.
I saw a gorgous large Moor with the most gorgeous fins, Owner had him as an only fish for years but had to go into a retirement environment. I took the fish , thought it was safe as he was an only fish.
Damn it if it didnt start the demise of my goldfish tank. He was doing fine, but then my oldest largest fancy tricolor one got sick and died, then another. The moor died and it was down to 3. I was devastated.
I had a fish store buddy that had been helping me for a few years and he always told me goldfish are for ponds or if you are willing to have a 100 gallon tank or larger for about 3 goldies.
He saw I was ready to give up and told me he would take the goldies and give me credit and he said I guarantee if you give africans a try, you will not fail, if you do , I will refund all you spend.
I took him up on it. My favorite goldies had died so...
I never looked back nor ever lost a fish to illness.
If you can keep Discus alive, you will not have a problem with africans. If you want color and constant movement and interaction, Malawan Mbuna are a must.
If you want a bit more serenity, the Tanganyikan's are amazing. A bit less hardy, but the Tropheous and the shell dwellers are so amazing.
They like very hard/ alkaline water, coral gravel and shells are loved by all africans and I always added salt to my tank. It was pretty salty and I think they like it, and bred like nuts and helped in heal any bites or scuffs from fighting.