Well in my personal opinion I would say the Texas is probably a female while the flowerhorn looks to be male. Granted its best to vent them just to be certain. If the Texas does turn out to be a female I would recommend putting it in a smaller tank to slow it's growth rate temporarily while growing out the flowerhorn till it's a good 1-2 inches bigger then the Texas. Most aggressive Cichlid females will not breed with a smaller male. The reason you need the male to be so much bigger is so the female has a place to hide where the male can't fit into. Also a nice soft sand substrate is good for breeding Cichlids of almost any kind. They really really like to dig and push the sand around where they want it to be. But most importantly is to whatch them like a hawk to make certain they are not just fighting continuously. A lil fighting now and then is fine but when it's back to back fighting none stop it's not good to keep them together anymore. Hope this helps ya a bit.
