genetic problem or disease?

[agcichlids]

We have a 55 gallon African cichlid tank with 6 cichlids. 10% of the water is changed every week and water is perfect. For the past year we have had 1male cichlid who will only eat about every other or every third day and shimmys and rubs on the glass. He has clamped fins and a red swollen vent. I don't believe its parasites because we've tried multiple different meds and none of them made it better. Also this has been a ongoing problem for a year and I thought parasites would have killed him by now. This is not affected any other fish in the tank Is their anything else this could be or is it a genetic problem with this fish?

[DogWalker]

Hello and welcome to the forums!

First things first, you say the water is perfect. For getting help, quantitative info is more useful than qualitative... Have you measured for nitrates, nitrites & ammonia? What are the readings?

As for only one fish being affected, bear in mind some fish just seem to be more sensitive to water quality than others (the explanation for that may be species related, or may even just be down to the genetic quality of a particular fish). It'd be a bit unusual that a parasitic problem would affect only one fish in the tank for that long, but again, it doesn't sound like a very heavily stocked tank so who knows. Which species, and how large are the fish?

[agcichlids]

I have red zebras, a rusty, a blue cobalt, a yellow cichlid with black fins (can't remember the name). The cichlid with the problems is a male snow white cichlid. They are all about 4 inches except for 1 of the red zebras which is 5 inches. We have had these fish for 2 years and only ever had one death. (A holding female got beat up). Nitrates 10ppm nitrites 0ppm and ammonia 0ppm

[DogWalker]

Ah, so one of those mystery illnesses (hate those!). Do you have a quarantine tank by any chance? If so I'd be inclined to get it running, transfer some established filter media to it, and monitor the fish in there for awhile. Keep water quality in the QT top notch of course. What do you feed them? Since the fish does eat I'd try feeding it foods high in roughage (eg: shelled peas, lettuce, cucumber, etc;) and not too rich in meaty proteins (fish meal, shrimp, etc.) to see if that helps, on the chance it's just chronic intestinal blockage. Might take some time for the fish to take to that stuff if it's much different from the current diet, but it will once it gets hungry enough (don't give in and give it treats just to see it eat, tempting as that may be). If it is an intestinal blockage problem some epsom salt in the water may help as well (say 1 Tbsp per 5-10g). Hopefully you see an improvement after 2-4 weeks.

If it's not intestinal blockage then the above steps may not resolve things, but... for the tough cases sometimes it's a process of elimination. There may be a treatable pathogen in play (though as we've already discussed, it'd be unusual for that to affect only one fish after a year), or it may be something beyond your control. (Fish do occasionally get ailments such as tumours, fish tuberculosis and things like that).

Good luck, if you go that route let us know how it works out.

Edit, if you don't have a QT tank the above measures can still be attempted in the main tank - subjecting the other fish to them will cause no harm. A QT is preferable though to give the ill fish some time out from the others, as long as the fish is not otherwise stressed in the QT tank (so provide some cover for the fish to feel secure).