Longest Possible Safe FW Dip?

[TimT]

I have given lots of fish a 15 minute fw bath to clean them of ick, velvet and flukes. If the bath is done correctly and the fish is healthy/strong enough there is usually never a problem.

You must make sure that the water is at the same temperature, pH and has been aerated for several hours to equalize the dissolved oxygen levels. Typically well water has low to no dissolved oxygen.

If the fish goes rigid with fins erect and maybe also twitching it has gone into shock and must be removed from the fw bath immediately. Observe the fish to make sure it starts to breath properly, if it does not then gently hold the fish near a powerhead so it gets a gentle flow through it's mouth. That helps carpet surfers if they are not too far gone.

Fish will normally lay on their sides in a fw bath.

If a fish has an open wound NEVER give it a fw bath.

You are dealing with some extremely sensitive fishes. IMHO Achilles are probably the most sensitive tang available. They are followed by the powder tangs.

For whether to FW dip an Achilles tang, I would NOT dip it if all the following were true;
there was a properly sized UV sterilizer on your tank,
the temp of your system was always stable(within 0.2°f),
the fish showed no signs of ick or scratching at the store and none of it's tank mates were scratching either,
it had not gotten cold during transport.

Hope that helps.

Cheers,
Tim