A little info about my tank, I have various soft reef, beginner reefs. The tank is 55 gallons in size. A couple months ago I bought a Yellow Tang. Upon purchase the Tang was an adolescent. I also bought a Coral Beauty the same day. In the tank at the time, there were around 30 snails and 20 hermit crabs, along with 3 or 4 Emerald crabs; a Scooter Blenny. The Tang and Coral Beauty fought over territory and ended up becoming friends within the first week. The Coral Beauty died weeks later by somehow swimming into the power jet.

Present day - the Tang and the Blenny still remain. They get along. I have attempted introducing several fish, 2 Lawnmower Blennys and a Six Line Wrasse. The Yellow Tang has killed every new fish I have introduced in the tank. I have also caught him killing snails and eating hermit crabs after pulling them out of the shell. There are some peppermint shrimp on the list too.

I feed the Tang once, mid-day. There is plenty of fresh algae for him to eat in the tank, also. Most is grown in my refugium. Is there anything I can do to prevent the Tang from killing new fish I put in my tank? Is there something specific causing this? Is he just a jerk?!?

  • I have had a few yellow tangs , and other tangs; I never found them to be particularly aggressive or attack shrimp. He will love Romaine ( no other) lettuce, maybe that will mellow him out. Feb 11 '18 at 21:36
  • @blacksmith37 Same here! That is why I find this so odd. I grow algae in my sump, the red stringy kind (tiger algae maybe?) and the long and thick blade type which he eats a lot of. In addition he eats some brine shrimp. I believe you're correct, perhaps feeding him twice a day will help. Also, I am not the best at keeping a scheduled feeding time.
    – snowYetis
    Feb 11 '18 at 22:23
  • I grew a lot of caulerpa which the tangs ate but still loved Romaine / Cos. Feb 12 '18 at 21:21

Once tangs establish territory, it can be very difficult to get them to accept any other fish being introduced to the tank. A yellow tang would have zero problem claiming even an entire 90 - 120 gallon tank, given the opportunity, so the phenomenon you're dealing with is, it's the tang's tank, and he's not wanting to allow you to invade his space with any other fish.

Best bet is always add tangs or angels literally the very last of any fish in the tank. But, with a 55, it's arguably way to small for a yellow tang to begin with, so you're likely going to have aggression problems no matter what or when you add fish.

If you want to add more fish, get a much larger tank. Keep the tang isolated until you have all the other fish you want to have in the tank. Add the tang very last of anything. Other option which I highly recommend is sell the yellow to someone with a large tank and get a bristletooth or kole tang. They are far less aggressive and their adult size is much more appropriate for 55 gallon tank. Even said, that tank size is very small for any tang, and most any angel including dwarfs if there are going to be other fish in there.

  • Why not try taking the tang out now, add another fish, and then after a decent interval and a tank rearrangement, put the tang back in? Feb 15 '18 at 13:53

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