I Have No Idea???

i also have this algae eater too which is by far bigger than the other two and think the three of them could be terrorizing every fish i put in. is this a possibility or am i being stupid

http://www.planetcatfish.com

I think the first ones are some type of Synodontis. Have a browse here and see if you can recognise them. Though they do look a bit like featherfins. You can see the fish properly to compare to photos on those sites. If they are featherfins, the last link gives their size as "12 inches, though 6 to 8 inches is more common in aquaria" needing a 4 ft/120cm long tank; and "should not be kept with any fish so small as to be considered food" So yes, they could be responsible for your fish losses, especially if they were small fish.

The bottom pic is definitely a plec, and I have a bad feeling it is a common plec ie a tankbuster. It looks very like the middle pic here. You could ID it better if you go to planet catfish and search through all the L numbers in the cat-e-log. But you'd need to set aside a whole day as there are so many of them  If it is a common plec, it needs a huge tank. The very conservative fish profiles on here say a minimum of 150cm long.