BettaBaby, the only way I can explain your previous experiences with overstocking small tanks with goldies and other fish is that your fish were likely just "existing" but not thriving... as they got older/bigger and their waste increased... the buildup slowly chipped away at their immune systems until they succumbed. Fish try their hardest to survive non-ideal conditions... and can live in a long time in these conditions simply due to their natural instincts of survival.

My brother, for example, kept a betta for 2 years in a 2 gallon tank that got waterchanges 4x A YEAR! (I didn't know any better at the time to correct the situation). The water was so murkey, you couldn't see the fish. But that betta lived 2 YEARS in those conditions. But I can assure you that they were two miserable years... but my brother didn't know any better... and the fish couldn't scream for help.

Temporarily, you can do daily 50% waterchanges to help keep the water params in check. But please test your water params before your next water change... I think it will tell you what you need to do.

I know this is heartbreaking... but unless you can make changes to keep them in a healthy environment, then you would be best to rehome them, or see if your best lfs will take them.

And keep in mind... not only do they need a larger tank to handle their waste and make their water parameters safer... they need the room to grow and swim. Think of keeping a dog locked in a pen all his life.... he wouldn't be a very happy dog not having room to run around and stretch... same kind of analogy.

As for the fish's problems... they will only get worse under these current conditions.

Also... pH doesn't need to be adjusted unless it is required for specific fish (like discus, some cichlids, etc). The types of fish you have generally accept a very wide range of pH levels... adjusting pH is extremely tricky, however, and often leads to fluctuations, which also stresses fish.

I would stop adding salt if you're not seeing any waste especially. Freshwater fish generally do not need salt all the time in their water... and with fish that are predisposed to constipation/swimbladder issues... I would avoid regularly using salt.

I hope the information we gave you helps you. Our goal is to see you be successful at keeping fish. We're offering information based on previous experiences of many fishkeepers with combined several years of experiences (and mistakes).

Michele