I did a bit of digging on FW feeder fish for SW predetors. I came across an article that is a good read. It would seem that FW feeders also do not provide the proper nutrition that a SW predetor would need. It might be fine for awhile but will cause problems over the long run.
If it were me I would make a serious effort to train him onto Frozen or Freeze Dried foods. It might take a bit of effort but the results will be happier for you and your fish.

http://www.advancedaquarist.com/issu...003/invert.htm

Train him to go on prepared foods or get a couple of convicts and grow ur own feeder fish. I used to have a channa bleheri and i put the 2 inch convicts in a 4.5 gallon tank...bred like clockwork.


Js

cool. yup i was aware they dont have the proper nutrition, thats why i stuff the feeders with flakes and cyclopeze first, i feed the feeders about 3 times/day.

I've tried to train him a few times, will get him trained eventually, he does take dead minnows now, he reaches right in the net... my next step will be to get him to take dead silversides from the net.