[souffle]

If you can see his testicles then it's fine so no need for a pic. Like I said if they are still cohabiting then it should be OK to leave them together as long as you watch them carefully. Bites would mean they do need separated. Try having another bowl well apart and also hide food in the bedding so they can forage for it. Do his teeth look OK? Have you got two wheels / houses and bowls? It's best to have two of everything however in this case as they are at this difficult age I might hesitate adding new things to the cage in case it tips the balance to fighting. The film is showing a dominance behavior now you have established that they are both boys. Young adult males of this age would be seeking out partners now so obviously living in a single sex group is not a natural situation for them at maturity. Fights can happen very suddenly and without warning. Prime time is around 4 months of age. The lack of weight gain in one is often due to them being constantly excreting adrenalin and being on high alert so even though he is eating he may be using all his energy that way.