It is said that CAE's become aggressive as adults especially to their own kind & those who are similar. In an aquarium setting they average 6" as an adult. They will not eat algae all of their lives & will need veggies such as zucchini, cucumber. I have 2 in a 46g that I've had around 9 months, they were approx 2" or less when purchased & both are around 4" now. I drop algae wafers a couple times a week (for them & the snails) & feed zucchini, cucumber or squash once or twice a week. They go NUTS for the veggies! There are a lot of or for stories regarding CAE's attaching to fish & killing them so be very careful of their tank mates.