white spot on powder blue

[cooksreef]

HELLO,
I have an 80 gal allfish tank and up until last week only about 8 smaller to med size yellow tangs , clowns , etc. All was going good and added a large powder blue and med regal tang, from a reputable dealer where all the fish looked great, Well those two fish were covered with spots after 3 days and since than they had 3 baths, a 20 gal change and 4 oz rid ich in tank which i have increased dosage. the other fish are almost all allright but on these the skin is beginning to peel, ???/

 

[audioguy]

Overcrowding and stress would come to mind first...
If your water parameters are ideal, it would probably confirm that
Good luck.

 

[elfdoctors]

You do have a lot of tangs in that tank. However, based on their known susceptibility to ich, and the fact that you are seeing spots, I would guess that you have ich. ALL fish should be quarantined for at least three weeks before they get added to the display tank.
The only reliable treatments for ich are hyposalinity (preferred) and copper. The sticky at the top of this forum describes how to do these. Rid Ich only has marginal effectiveness as one stage in the parasite's life cycle so is not usually recommended.

 

[cooksreef]

THANK You.
The tangs are all dead and so is the clown fish that I suspected to contamate the tank. I did not have a qt tank at the time. Is a freshwater bath a good idea. And if so do I give it before or after acclimation? In any case , no more tangs for me. My coral beauty, puffer, 2 clowns, and dottyback are all fine. In all I had less than 30 in of fish.

 

[elfdoctors]

Freshwater dips are no longer recommended. They do not work for ich (they will make the larger trophonts fall off but the smaller parasites are protected in the slime layer of the fish) and they are moderately stressful for the fish.
A QT is really a necessity in this hobby. Buy one (or at most 2) fish at a time and make sure they are healthy before adding to the display.
BTW, your other fish should be assumed to have ich also. They are all more durable fish and may be able to develop a limited immunity to ich. However, if they are not treated, any future tangs (or other nicer fish) are likely to get infected again.
A good ratio to start out with is 1 inch of fish for every 5 gallons. When you calculate stocking ratios, some people use 1 inch of fish for every 2 gallons but this method requires you to use the ADULT length of the fish. Older tanks (with more experienced owners) can often handle this overstocked ratio). Yellow tangs should get to 8 inches. Unless this tank was over a year old, it was probably overstocked already.

 

[cooksreef]

I treated with malachite green and stress coat before they all died then did a 20 gallon change after, skimmer still foaming. Can I use formalin, which I have, or wait 30 days, . Did not hypo , uv is on.

 

[elfdoctors]

Malachite Green is a medication for freshwater ich (which is a completely different illness).
The only reliable treatments for saltwater ich are hyposalinity and copper.
Formalin is used for saltwater infections (including black ich) but will not work for regular (white) ich.
Waiting 30 days with your tank completely fishless (inverts are okay) will eradicate the ich that is still in your tank.