Your tank is plenty big enough. Ive bred sevs in as small as a 75. Some pairs never get it right and will eat the eggs every time or your other livestock is getting to the eggs because they aren't defending hard enough. They will lay on your rocks or wood so you can move that to a nursery tank once the eggs are fertilized. If you do that youll be responsible for picking off dead white eggs. Expect heavy losses of eggs and almost as heavy on fry. The fry take a fair amount of time to get to 2" sale size and by that time will start murdering each other so find a shop that will take them at an inch or be prepared to have a few tanks set up to separate them.