Can anyone help diagnose my goldfish? I am unsure of how to treat them

[Cara Harrington]

I've had 3 common goldfish for about a year in a 10 gallon tank.  We just upgraded to a 75 gallon.  About a month ago I decided to treat my biggest goldfish for what appeared to be mouth rot.  He had white soft looking strings cloudy stuff hanging from his lips, mouth was darkening and he looked to be gasping and trying to bite the white stuff away.  I went to Petsmart and the fish lady gave me Erythromycin,  I treated the entire 10 gallon tank according to directions.  It seemed to help a bit but now that they're in the 75 gallon tank and the lighting is much brighter, I'm able to get a real good look at these guys and the big one still has a mouth problem, he's struggling and stressed.  The two smaller ones look like they're missing scales.  The advice I was given on that is sometimes the fish will bit each other scales off if they're stressed or in too small of a tank.  I'm unsure and can't tell what's going on so I dont know where to begin with treatment.  I use aquarium salt and water conditioner for every water change I do.  Over the course of the year, due to my lack of experience, the tank did get dirty real quick and I learned a lot about keeping goldfish and how much waste they make, plus my husband loves to feed them, a lot!  I'll post some pics.  If you can help, I'd really appreciate it.  I ordered 2 Ziss bubble filters from Aquarium Co-op because of Cory's reviews on youtube! Also, I have a Tidal 110 filter coming today.🐟  I can share the water quality with you...I have the 5 in 1 test strips or the kit that tests each thing individually. I have to get a new temp gauge today

[Colu]

What are your water parameters and looking at his mouth it could injury or bacterial infection that caused what your seeing I would add aquarium salt 1 table spoon for 2 gallons for one week just remember to only put the amount of salt back in that you take out so if you do a 10 gallon water change put 5 table spoons of salt back in and increasing water changes  if after a week your seeing no improvement then I would do another course of maracyn the missing scales more than likely happen by being kept in to small of a tank try adding some floating plants like duckweed water lettuce that will remove nitrates and the goldfish will snack on them 

Edited December 29, 2021 by Colu

[Cara Harrington]

On 12/29/2021 at 1:05 PM, Colu said:

What are your water parameters and looking at his mouth it could injury or bacterial infection that caused what your seeing I would add aquarium salt 1 table spoon for 2 gallons for one week just remember to only put the amount of salt back in that you take out so if you do a 10 gallon water change put 5 table spoons of salt back in and increasing water changes  if after a week your seeing no improvement then I would do another course of maracyn the missing scales more than likely happen by being kept in to small of a tank try adding some floating plants like duckweed water lettuce that will remove nitrates and the goldfish will snack on them 

I'll get the parameters shortly.... I just transferred the 3 goldfish from 10 gal to 75 gal yesterday.  I added about a cup of aquarium salt. box suggests 1 tablespoon for every 5 gallons of water in your aquarium.  What's the best way for me to get the duck weed and about how much?  Also, thank you very much for your help!!

[Colu]

Duckweed you can get from most garden center or online it reproduces really quickly

[Flumpweesel]

Keep a tight eye on your water the change in tanks could mean you are in a fish in cycle still and they can trip to toxic levels pretty quickly (I had a similar issue with a tank upgrade for big fish). So expect to be doing partial water changes daily (just enough to keep it safe and let the bacteria grow).

Keeping the water clean will be the best thing you can do for that fish who is probably still healing from whatever the meds killed.

Fingers crossed for you that this all goes smoothly.