Are catfish colorblind?

Hey I have a problem with a feather fin catfish help plez?

• Hey I have 2 featherfin catfish previously 4 female betta fish and one male betta fish . I looked in my tank a while ago and one o the female betta fish was all beaten up . Not in very good shape at all , at first I thought maybe it was my male betta had a go at him but he was just swimming past him and not really doing anything he's really dosile so it couldent really of been him , and for anyone who says females and male can't be kept together I kinda disagree as of what happens later,then the female drifted over to my catfish and the catfish really had a go at him , the female was always real small compared to all the others , and just to clean this up the catfish is quite big even thought when buying them the guy said they only grow to about 6-8cm =/ so I held the female in a net under the water obviously for a while but she was too weak and died , just wondering what I should do because I have had the tank a long time going for about 2 years now and the catfish has never gone for another fish like that before , I don't really think that he would attack any of the other females because they are quite big compared to the one that died . And there are no eggs or anything around the catfish or anywhere he likes to " hang out. Cheers any help would be great , should I take him out or just see what happens =/

• Answer:

  Synodontis are known for eating smaller fish and being territorial.