Had to google hydroids to see what they were. Found a link about natural cure: nudibranches and key hole limpets. Also came across a chemical treatment but take it for what is worth. I have no experience with this species. http://www.fusedjaw.com/aquariumcare/dwarf-seahorses-as-pets/
dangit lol thankyou for your reply. I need to wipe them out and the only thing thats suggested is dog dewormer and I cant help but being skeptical of that one!!
I had them in a tank a few years back. The only thing I found to do anything was kalk paste via a syringe. Not ideal, obviously, in a seahorse tank. No natural solutions that I could find.
I'm sure you know that hydroids are coming in with your BBS so you are likely to get them again. Amphispur and I attended a presentation by Dan Underwood this summer where he identifies that he disinfects with hydrogen peroxide. Here is a web article that describes his technique: http://www.marinebreeder.org/forums/viewtopic.php?f=144&t=6664 . He gets his H2O2 from manufacturing sources, but identified beauty supply sources as a potential source also.