It is a Vieja or Paratheraps species, hard to tell at this size since a lot of them look very similar when young. Could always be a hybrid of several vieja types as well.
Possibly a synsiplum/melanurum, bifasciatus, fenestratus. If I had to guess.
Maculicauda can reach around 12 ", as can many of the Vieja it resembles.
A 75 gal is a tad small for many, I wouldn't use anything small than a 6ft 100+ gal myself for an adult.