Cichlid Gil torn..swimming vertically

[Drbales]

hey guys..new to the forum, 1st post. Recently added what I believe to be is about a 3-4inch lemon Jake to my established 75 gallon African aquarium. There are about two other cichlids in there that are his size, while all the others are at least an inch smaller. I acclimated him to tank with light turned off and no one else seemed to pay any attention. Flash forward a day or two and I notice he is swimming vertically and not eating. Upon further inspection I found that his Gil beneath his head has been partially torn. I have no idea what could have caused this, but speculate that it could only be from aggression..I just don't see any fish large enough to inflict such damage. I will attach pics below. Please tell me if you have any ideas what could've caused this and how I can treat it. I have put him in a floating breeder tank so that he doesn't have to struggle so much to keep himself balanced. Water levels are normal. Desperate for help. Thank you

 

[Rbishop]

What exactly are the other cichlids and how many of each?

 

[Drbales]

What exactly are the other cichlids and how many of each?

Admittedly, I began in the hobby pretty ignorant to the importance of researching before purchasing and mixing compatible fish...so I don't know what exact species they all are, despite quite a bit of looking online. Fortunately, have yet to have a fish die due to aggression. Here's what I know I have:
1 m Jewel cichlid , 1 female jewel
1 m Taiwan reef
1 m Apache cichlid
3 red zebra
1 m flame back
1 f flame back
1 m Victorian cichlid (forget exact species)
1 m blue auratus
1 f yellow auratus
1 m Johanni
2 smaller jakes I believe to be m, and 1 larger Jake m
1 Kenyi sex unknown ( coloration is like male but I've read that females can adapt make coloration, or maybe it's vice versa
2 female bumblebee
2 yellow lab

On a side note, the jewels are on their third cycle of caring for fry ( the first two generations are in separate breeder tanks). I suppose they are a pretty likely culprit. We have previously tried dividing off the jewels into their own section of the tank with their fry but this always turns into a mess as other fish find a way to aways get on other side of divider and the rest of the tank is simply too small for the other fish.

Also, I have since taken out the ailing cichlid and have put him in a bucket with a few decorations and an air stone. Treating him with aquarium salt and melafix.

Will also let you guys know I am in processing of purchasing a 150gallon.

 

[Tifftastic]

If you have fish caring for fry, I'd be willing to bet that those are the culprit. However, it could be any of the fish on this list, Africans are pretty rough on each other. Adding one fish at a time to an already established tank is always risky. Its best to add them in groups and to rearrange all decor completely.