dying fish

[BLEEZY]

have a 15 gal with 15lbs fiji rock i started out with a purple dottyback a yellow tail damsel and a mandarin goby they did fine for about a week then the damsel and goby disapeared completely and my amonnia didnt move and i couldnt find the corpses so my fish store told me to look for some kinda crab or mantis shrimp so i took out the rock and didnt see anything. i got a percula clown and a young sailfin tang from the wholsalersthe percula died i replaced it that one died got a big mandarin goby still have it and its getting munched up on its fins. ive had a guy from my fish store take a look at my tank and he couldnt see anything. someone tell me what is going on here.

[Cella75]

Damsels can be very aggressive and territorial fish. It may be your damsel munching on the little guy. Also just an FYI 15 gallons is way to small for your Tang. I had a 12 gallon and got a Tang becuase I was a salt water newbie, I had him about three weeks before he died, he totally stressed out with each water change and got infections

This is just a blurp from an online fish store about Sailfins.
A 125 gallon or larger aquarium is necessary to provide plenty of swimming room. It is aggressive towards its own species and conspecifics at times, but peaceful towards other fish, so keep only one except in a very large tank. It eats filamentous algae.

If possible try to take him back or you will ends up losing him. Sorry for the bad news but take it from someone who already make that mistake

[dobejazz]

How long has your tank been set up?
Mandarins are very difficult to keep they do best in large established systems with lots of Live rock. Sails Fins also require a lot of swimming space

[ChrisPrusha]

Good advice above.

I wouldn't put more than one small fish in a 15 gallon. With respect, your local fish store is giving you poor advice while taking a fair amount of your cash. Any other LFSs in the area you could try?

Consider taking the mandarin back...frankly I don't think he has a chance of surviving in your 15 gallon. Btw, how long has your tank been set up?

Finally, welcome aboard!! w0000000000000t!!!