if the carpinte is male then the tube should be showing all the time anyways, its not out of there nature for cichlids to interact with each other this does not meen that they are a pair.
i hope they dont breed, because knowing the likes of you, you will sell them to the LFS as texas or JD at .5" and then there will be tones more hybrids out there.
it probably chases the other texas because its the dominant one out of the 2 (or how ever many you have in ure 1 gallon beer glass)
get rid of the JD and texases (and what ever else you are keepign in that cup) and keep something which will not out grow your tank.
and then when youve bout 2 neons 2 cardinals 2 guppys and a bristlenose pleco, never go to a fish store again and send someone else to buy your food/dechloriniser.