Question
My 2 year old grandson has a pet koe about 8 inches long that is floating on his side after my daughter left the garden hose in their yard pond for hours. Three goldfish have died, eight are doing great but the largest one is struggling.  I have brought them inside and put them in a 30 gallon well established tank.  Will alot of oxygen help, or is he domed?

Answer
Logan,

Fish exposed to too much chlorine get burned gills.  Added oxygen and stress coat will help until they heal.  If they are too badly burned, they can't recover, sorry.

Get you a bottle of dechlorinator to keep on hand.  If this should happen again, quickly get dechlorinator into the pond.  The quicker this is done, the less damage you will get.  You can usually save your fish if you can get it in within a couple of hours.

Good Luck,

John