I think that it would be possible for you to put in dwarf seahorses. Probably a pair. I have seen a few biocubes converted for the dwarf seahorses hippocampus zosterae. Google this and take a look. Keeping this in mind, it might also be cheaper to just buy a tank for them, but its up to you. I would also suggest going to your Lfs and asking them what they think would be suitable.
hope this helped
