Hi there, what is the length of your fish? Why I ask is to me this fish does not look like a moorii. Puzzled by its shape! The Pseudtropheus lombardoi(kennyii) are known to be quite an aggressive fish, especially the male. Could be them giving this fish a hard time, especially if they are a bit larger than it. No harm in treating as fish will eat properly when totally healthy. Monitor your tank for a couple of days to see what is happening. Great looking fish and it would be a great pity to loose it.
he's about 2.25 in. the rest of my fish are about .5 in larger. the kenyii and labeotropheus are the two runners of the tank. ive had my dolphin for about a week now and he got picked on at first, but he's no longer getting picked on as long as i'm around. like i told honda12, if anything the dolphin is picking on my venustus. he is a pretty harcore fella also though. i don't believe believe the kenyii is picking on the dolphin in particular.
i think the moorii that you are referring to is a tropheus moorii such. (i pictured a few)
my fish however, is a cyrtocara moori. they are a totally different genus and specie.
This latest pic gives me a better look at the mouth. They have a very distinct mouth which seems to have something to do with the hump they eventually develop. Your fish will soon start to have its forehead start bulging out. The correct name is spelt "Cyrtocara moorii". The pics you have posted are Tanganyikans. Really aggressive fish these are especially if you don't haver enough of them in the tank. These need to well and truely overstocked.
My venestus tends to swim around minding its own business. The same goes for the livingstonii. I wonder if the others know these fish are actually piscivorous?