Thanks for the help.
Could the fact that some of the fish are very young and have not matured properly account for hybrid look? Perhaps I need to wait a few months to a year to get a better idea of what they are. The young fish were in a tank altogether, not labelled with names or except for 'Assorted Malawi Cichlids'. It seems I might have been done by the fish shop.
I've added a few more pictures to my gallery, numbered them, and put names where I've been advised as to what they are.
I bought the tank as a secondhand setup. It came with all the fish, which included 7 catfish (Synodontis decorus , Royal Panaque, Synodontis multipunctatus and a couple of others I've not named yet) and 10 Malawi Cichlids (Livingstoni, Blue Dolphon, and whatever the others are).
I've thinned out of the cats since then. Although it seems that I need to lose some more. How exactly do I go about doing this? I've tried ringing around local fish shops to get rid of the Dolphin and the Livingstoni. The fish shops don't want to know. They were attacking the other fish as they are much bigger than the rest. I moved them to my sons tank, which is too small really but it's only for a few weeks, until I can pass them on. I then added the 8 younger fish to my tank. I expected to lose some, but they are all quite happy and have grown a little since I got them.
I've added my own decorations since buying the setup 3 months ago e.g. ocean rock and resin mock wood ornaments. There's plenty of hiding spaces for cats and cichlids, although I'm going to add some more ocean rock and some bog wood for the Royal Pleco at the weekend.
The tank is 36" x 15" by 15" which according to the calculator I used is a 29 UK gallon tank (35 US gallon). I have 2 filters (a Eheim Pro II external and a Fluval 304 internal). There are 5 catfish and 15 Cichlids.
Thanks