Minimum size tank for single FH

[RD.]

The width of the tank is more important than the length of the tank when it comes to flowerhorns.

IMO they are both equally important, just as they are for any large bodied CA type cichlid. While I agree that an 18" width is ideal, a FH will defintely utilize the length of a tank as well. I have a couple of my FH in 6ft 125's, and while I'm quite certain that these fish would be fine in 4ft tanks, at times they certainly like to flex their fins & swim in high gear from end to end. The extra volume of water also aids in keeping parameters stable.

IMO if you are considering a 75, for the small difference in price, you might as well get a 90. Same footprint, but some extra volume of water, and IMO a nicer viewing height for when your tank buster matures.

 

[BIG_ONE]

I would agree with RD here, I might as well buy a 90 instead of a 75. Same foot print overall, just higher for nearly the same price. Then if you get a 90, I might as well get a 120 for just a bit more $$$. And cheap if you come across the right person on craiglist.