Very nice, looks like some banded pipefish. How long have you had the tank setup? Did you add the four seahorses all at once? The tank looks spectacular, can you tell us more about the setup?
I started it in December and yes that is banded pipe fish. The sea horses were introduced yesterday. There is also 2 banggaii cardinals 2 red scooters and a red dragonet too. As well as 3 peppermint shrimp and sand sifting stars. I originally had 4 scollies and a plate coral in there but once I put the ponies in I relocated the scollies and the plate coral into my other tank because the literature advised against housing such corals with sea horses. I replaced them with Fiji Zoe's on Tonga rock to the tank to add some colour from my other tanks . I added sponges in March to the tank for additional colour and for hitching post for the ponies.
Very nice tank ! It will be interesting to watch this as it matures ! I have to do some reading on what will tolerate the lower temps in the tank and what won't hurt the seahorses as well.
Looking good but be careful with the banded pipefish. They are often not captive bred and can carry diseases that the seahorses are not immune to. Watch all inhabitants carefully and I suggest you have a 10 gallon tank available for quick quarantine if needed. The tank does not need to be cycled and can remain empty until it is needed but it is a good thing to have on hand for all seahorse keepers. I like the look of the tank.