Very hard to tell from the pic, If it came from the gulf there are 2 options. A merc or a vulgaris "As far as I know" Once he/she gets in the tank take more pics and post them. Looking forward to seeing this octo more.
as far as feeding goes, you live in Texas, do you have bait shops local. I would get some small bait shrimp and try 1. If thats to big try uncooked pieces of shrimp. If you can get fiddler crabs they are good also. pretty much anything they would eat in the wild. As far as how much. As much as he/she will eat but dont leave uneaten food in the tank.
How big is your tank? I ask because if this is a vulgaris your going to need a lot of space. If you check out my thread named "Intro Casper" you can get an idea of what your in for. If its a merc then he/she is going to be very nocturnal. I could be wrong on the species but here in FL there are just 3 species in the gulf.
LOL, @sirreal, we do have a couple more in the Gulf, O. hummelincki, O. joubini (or so it is said, have not actually seen one but Texas is a known location), and O. briareus (your third option I suspect). However, the unnamed are not an obvious option for this one. More pictures are needed. It would also be helpful to know the mantle length to arm length ratio, where it was purchased (or better, origination), a description of the different skin bumps when they appear and what colors it displays.
Octopus ID is a particularly difficult subject outside of the fact that one animal can look like another at any given time because the experts (and scientific advancements) change the nomenclature. At one point, it was declared that there was only one dwarf species in the Gulf, Octopus joubini. For year O. mercatoris was labeled O. joubini until it was shown that there are at least two species, one that lays small eggs and the other that has large eggs. For now, we call the small egg animal O. joubini and the large egg animal O. mercatoris. The later may change . I have also seen an official reference to O. hummelincki as a dwarf (but can no longer find the source ). This animal has flip-flopped names from O. filosus to O. vulgaris to O. hummelincki, the later being the current official (but contested) name (many octopuses have been classified and reclassified to and from O. vulgaris). You can add to the confusion by noting that scientists have reclassified Octopus into several other genus. We now have Abdopus, Thaumoctopus, Enteroctopus, Wunderpus, Amphioctopus .... I don't EVEN look at the names and name changes for squid !
He's out till about 8am then sleeps all day. He's usually out playing taking thing apart in the tank sometime early mornings , when I get up around 6am he is waiting on me to feed him. I gave him fiddle crab and some Krill this morning then went sleep in his shell. He seems to be a piglet. He also seems to get mad at me when clean his tank. Turns red and charges me sometimes, when I take he's left overs out. He keeps taking the thermometer and sticking up in the conch shell he sleeps in. I think he doesn't like me taking his toys. I had to place it in the sump because I was afraid he was going to bust it. He is funny.