This is pretty biased information, nothing is certain in fish keeping. I've done many grow outs with size gaps like that with my shovelnose over the past 4 years with no problems. Not saying it's that way for everyone but it can be. As long as you feed both plenty I wouldn't think it would be a problem. I've also found that frequently people lose arowanas to TSN's but they are slender body fish, I've never found one of my catfish to try and eat another catfish tank mate or in general any other larger fish to mess with my catfish tank mates. Just like in the wild most catfish aren't on the menu of other fish species and seldom are they canibalistic towards their own species. If you have a 265 put a divider in the tank for now and keep the Tig seperated while it grows up some that way you don't have to get rid of either if you're that worried about keeping them together. ~Trent