Best of luck to you with all these little cuties, John!

I believe that there are better meds than Tetracycline because of the resistances to this one, but the others are better equiped to answer this. Although, now that it is started, you shouldn't stop early.

Along with Ash's info about salt from earlier, plecos aren't very tolerant to salt so you wouldn't want to add salt to his/her tank.

Sounds like you got a common pleco, which means they get huge and this one will need a bigger tank in the future. Sexing common plecos can be tricky if you don't have another one to compare too. Females tend to be more rotound.

A mixture of algae wafers and fresh veggies is a good diet for plecos but they do enjoy just about any food offered and tend to enjoy frozen (but thawed) bloodworms and other frozen foods, but this should be considered a treat for them. If you haven't tried zucchinni, then I recommend it. It has always been a fav of mine. Attach the veggies to some sort of sinker or veggie clip and leave it in the tank for 24 hours.

-Shelly