First lovely fire eel, secondly, move the rtc x tsn out the tank he will be able to eat him , i watched a 3inch rtc eat a 8 inch worm it did take him half the day, and eels are like worms.
Ive keep on to about 12 inch then moved him on, great fish to keep mine hand feed the first day at 6 inch , just feed blood worm and prawns but cut the prawns in half, easyer for them to eat.
Goodluck with him.
Dav.