He has a normal apetite and he is eating without a problem.

Water parameters are:

 Ph: 8.4

Amonia: Not detectable

Nitrates: Less than 1 measured with Tunze kit

Phosphates: 0.04

Alkalinity: 3,8 meq/L

Calcium: 420 ppm

Magnesium: 1250 ppm

Temperature: 27ºC

To me it looks like a cut and it has like a little white string coming out from the cut. The problem I have is that is going to be very difficult to take him out of the tank. He hides in the rocks and it is impossible to catch without taking apart the tank.

What would be your recomendation ? In my country is very difficult to get some good fish medicine, but I do have on hand Kent RxP, Seachem Metronidazole and Seachem Neoplex and Seschem Stresguard. In my tank I have some corals so I also need to think about them........

135 gallon Deltec Starfire SPS tank

Welcome to MarineDepot.com and this forum.

Thanks for posting a pic and pertinent information, this does help with coming up with a diagnosis and a plan of care.

From the pic, it does appear as it could possibly be an injury.  I do not see any redness or deep ulceration.  The white thing you describe could be mucous or scales.

The key here is to get the fish to heal without it developing a secondary bacterial infection.

If the wound/area in question looks the same today, I would probably enrich the food with vitamins, beta glucan and selcon.  These will help boost the immune system and promote healing.  Keeping the water parameters pristine and decreasing stress are also imperative.

If the wound/area in question is spreading, showing signs of infection (redness, ulceration, change in fish's behavior, eating, etc).  I would place the fish in a separate quarantine/hospital tank to treat.  I do not advocate adding any of the "reef safe" medications to the reef.  Metronidazole will not help as this is for internal parasites/infections.  Kent RxP is for treatment of external parasites - ich.   Seachem states that its product StressGuard "binds to exposed protein in wounds to promote healing of injured fish and to reduce the likelihood of primary and secondary infections." - may help, watch your tank closely if you add to display tank.   Neoplex is your best option if this becomes bacterial in nature.  I would not add it to the display tank, but rather in a separate tank.

Here is a good link/thread on catching fish in a display tank:
http://reefcentral.com/forums/showthread.php?s=&threadid=707656

If you can get some medicated fish food (pellets) that could be an option as well.  The key here is that you only feed the medicated food for 7 - 10 days to ensure proper therapeutic levels to effectively treat the bacteria.  Jungle (www.junglelabs.com) makes a food called "Anti-Bacteria".  It contains sulfathiazole and nitrofurazone.  For bacterial infections, I use Nitrofurazone, or Kanamycin or Mardel's Maracyn-2 (minocycline).  Seachem's product called Focus is a polymer that you mix the antibiotic with and feed to the fish.

Again welcome, thanks for sharing and please post updates/pictures.

Best of luck.

Thanks for your help...... I can't wait to go back home and see how the male Anthia is doing. It took me more than a year to be able to get this Anthia and now I don't want to loose it (in my country is very difficult to get anything related to the hobby.....).

I'm travelling to the US on May and I will make sure to buy some Nitrofurazone, or Kanamycin or Mardel's Maracyn-2 (minocycline) to have in case of new injuries. I will also make sure to buy some medicated food since I can't find it in my country.

I will keep you posted of what happens....

135 gallon Deltec Starfire SPS tank