On the subject of which fish are typically suitable for seahorse tanks, cardinalfish (notably, bangaii cardinals), gobies, pipefish, blennies, basslets, dartfish, and other small/very peaceful fish are generally fine.
Since the introduction of any other fish increases the likelihood that your seahorse will be infected by some foreign pathogen (and in turn, the likelihood that it will die), you should be very careful the source of your fish. Don't mix wild-caught tankmates with captive-bred seahorses (and vice versa), if at all possible. Ideally, you should try to get your seahorses and their tankmates from the same breeder. To that end, I recommend getting both tankmates and seahorses from either Ocean Rider or ORA. ORA has a variety of suitable, peaceful tankmates to choose from, and they seem to have a lot of H. Kuda in stock, right now. Ocean Rider offers several different species of seahorses and for tankmates, they offer captive bred banded pipefish and bangaii cardinalfish.
If you do decide to go through with it, good luck!