Chillers can be avoided if you have whole house or at least room control of temperature. With AC you can keep the temp no higher than about 72/73 and the tank temp shouldn't get above 74.
H. fuscus have not been available for quite some time now in North America, and to the best of my knowledge the ONLY available smaller species are from seahorse.com but at prices that make it VERY unwise to spend for if you are not already an accomplished seahorse keeper.
Their H. capensis would be OK but they have been out of stock also.
Actually, I just checked and their H. fisheri are also out of stock so unless someone knows of a source of any of these smaller ones, they are not as of today, available.
H. barbouri IMO are too large as adults except for in a 25g tank with extra husbandry and extremely well kept water conditions, better than for any reef tank would need. Barbs are the most susceptible seahorses of any species I've kept over the years, for pouch emphysema, and it can be a tiresome chore dealing with this problem repeatedly when water conditions aren't excellent.
Unfortunately, the hobby test kits available to us do NOT tell us when that water quality is lacking to the point it is detrimental to the seahorses. i.e. for conditions that cause chemical imbalances in the seahorses and the conditions that lead to nasty bacterial infections.