Sick Fish

by Kelly
(SF Bay California )

We started a 55 gallon pond about 8 weeks ago with just water and 3 pond hyacinths and a pond filter, 2 weeks later we decided to get fish and traveled to a pond store and bought 9 mosquito fish an appropriate pond filter and test kit and products to condition the water.

Another 2 weeks and everything testing perfect we brought home 3 comet goldfish each body size about 2-2 1/2". All was well until one of them started looking sick about 4 days in. Water quality was good. By the time I found your website it was too late but another fish started seeming sick.

We followed your advice and added aquarium salt to the pond in an about 1/8 water change. It worked! They swim and eat and seem happy but yesterday I noticed one has an ulcer and upon closer inspection it’s bigger than yesterday and the other fish has black marks on it I don’t remember it having before.

They are eating and swimming not acting sick-yet, but what should we do? Bring them out of the pond? Isolate them with different treatment? Remove the hyacinths ( which seem to not like the added salt but the fish love swimming under them). Any advice is appreciated! I’m thankful we decided to start with affordable comet goldfish this would be harder to swallow if we went with koi but the comets are so cute!

Please help! Thank you!
Kelly

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Grants Reply

Hi Kelly

Your approach to setting up a pond is commendable, taking your time and using a water test kit to check water quality before introducing fish is the smart approach.

It is also pleasing to have someone use body length when indicating fish size. A 3” Comet can have a tail the same length as its body, but it isn’t a six-inch Comet, it is a 3” Comet with a three-inch tail. A six-inch Comet, although only twice the size, will have a body weight 8 times that of the 3” fish.

I digress.

The only concern I have is, did you treat the fish for parasites?
You can almost guarantee store bought fish have them unless it can be proved otherwise.

Ulcers are often caused by parasites damaging the skin allowing bacteria to attack, and the black marks could also be signs of parasites. The black marks are the skin healing which will soon fade away to orange/gold. The salt may have killed some parasites if you dosed at one tablespoon per gallon.

The actions to take now are:
Leave the pond set up as the filter should now be cycled (ammonia should be zero).
Remove the hyacinths as they won’t appreciate the salt.
Purchase a parasite medication such as API General Cure or PraziPro, anything with Praziquantel in it. Treat the pond with it. It is safe for fish and the filter.

If there will be a delay to purchasing a parasite medication, and the salt is below 0.3% solution (one tablespoon per gallon), increase the dose up to that level. Yes, it seems a lot, but Goldfish tolerate salt very well.

Note, salt will not kill flukes, which is the most likely parasite hence the parasite medication.

Once you have the medication, the salt level can be reduced down to around one tablespoon per three gallons to aid healing. However, the fish with the ulcer needs the salt to be at 0.3% solution, so I would suggest treating it separately in another container.

Keep the water pristine as many deaths occur in hospital tanks because the water quality drops.