I've got my motoro in with a 14-16" giraffe cat and a 12" niger. and they do fine. but DB is right you need to feed A lot. To make sure the rays gets enough food. Rays are just so much slower then catfish that you need to make sure that the food can get to them. If that means adding a lot more food then usuall then so be it or if it means that you have to add so much food that you have to scoop some out that doesn't get ate to make sure the ray is full then so be it.
One word. pancake. Might as well put maple syrup on it. If this will work, you need a big enough ray and big enough tank. Not that I would try it. With weird combos like this, I always hear of it working...and then a few months later the thread abruptly ends. Either the person admits to it ending bad, or dissapears. But this kind of experimenting is good for the hobby, someone needs to figure this stuff out.
This is my plan once the TSN moves out. The rays are still new and are still on earth worms, while the TSN gets tilapia and shrimp. Every now and then the TSN will grab one of their worm chunks, but not so much that the rays get nothing. I also try to feed them at opposite ends of the tank which seems to help because they both know where to look. They seem to be getting along fairly well though.
so I will get tigrinus, now that I heard all your opinions I decide it and I think they are better for my rays.
I just ask for RTC because it´s one of my favorite cat fish
personally i wouldnt keep rays with rtc's unless i had a pond. a large redtail is scaleless and the body is very soft. the ray could one day could have a mood swing and use its sting as an act of "get-away-from-me!" and you will have a dead redtail.
but, both together in harmony would make an amazing set up though.
We have never kept a redtail with our rays, however we have kept one seperate. He was about 14" when he proved his appetite was bigger than he was. We had a 8 or 9" pleco in there with him. He had gotten along with him fine for months...we came home one day...no pleco and the RT was sitting at the bottom with the pleco tail visible in his mouth. It was not pretty. We were sure it would kill the RT too, but somehow he digested pleco. I don't think he moved for at least a week and then didn't eat for another week. It wouldn't be worth the risk imo. You just never know when the mood to devour something will strike the RT.
We have 2 Synodontis Decourus with our rays now. They are peaceful and do a great job cleaning up any little scraps from the rays. And they are beautiful.