Most "Texas" cichlids found in local fish stores are probably either aquarium strain (hybrids of cyanoguttatus and carpintus) or one or the other.
Real Texas (cyanoguttaus) in my opinion get too large for a 75, I've see males easily top 12", with height to match, although its takes a few years to reach that point.
Carpintus get that size over time too.
These days there are many location variant carpintus available from different parts of Mexico (calling them Texas is a bit of an oxymoron).
Below is Herichthys carpintus "location Chairel".
At about a year old below

Later on, after it outgrew a 75 dal

They are omnivores, that graze a lot of algae in nature, so a pellet with a high spirulina content is a good idea.
Another Texas look alike is Herichthys tamasopoensus that doesn't get quite as large, but you may not find in LFSs, only available from cichlid specialists.

there are also the similar species H minckeyi and H deppii (which has a bit more color) from cichlid specialists, are a bit more challenging to keep, and a number of line bred aquarium strain versions like red Texas etc
I also agree, educating yourself on the nitrogen cycle and different types of filtration is important.
Especially because you are choosing fish that require optimum conditions to stay healthy and look their best, and which as they grow need more water changes and care the older they get.
Whether or not Cuban or Texas, any slack off or not upgrading of tank size as the grow,can lead to disfiguring scars and at best a drab pouty look.