Am very frustrated: My 45 or so goldfish and several mosquito fish were so happy. Then literally overnight they stopped eating and within days died off.
The day the trouble started the outside temperature soared to 95 but the water seemed cool enough. Moreover, the center of the pond is 4 feet deep.
In happier days whenever I’d feed them they would snap and race around their pond. The pond is an in-ground hot tub covered with a non-toxic triple liner designed for fish that cost me $300. We live in Pasadena, CA where the weather is generally moderate.
The goldfish were rescue fish destined to be eaten by Pet Smart customers’ carnivores. So they were at least spared whatever terror was in store for them.
After they started to die off, I changed almost all of the water but not all because there were some fry I was attempting to save. In hindsight I wish I had gone 100%.
I repeatedly tested the water with a kit and also at PetSmart. Then I put some new goldfish in—all of which died within days. The water was hard so I added the proper amount of salts. The ph was around 7. The nitrite level was borderline stressful, so I added a bottle of stress coat. Still no luck.. All other readings (ammonia, etc. were normal).
I had made a filter using bio balls and ran a small pump constantly with ok aeration. Admittedly it could have been better, as the balls never really looked that dirty. Moreover, because a raccoon had punctured the liner, only 3 months earlier I had completely drained the pond and did with no lose of fish.
After the disaster struck and following the water exchange, I built a massive filter and added a heavy duty pump that made the water crystal-clear—but it was too late. Another batch of new fish died.
After draining the pond, I realized too late that some of the fish that died had sunk to the bottom and possibly continued to contaminate.
Half the pond’s surface was covered with 2 types of water lettuce. I have now 100% drained the pond and have discarded the lettuce for fear that it is contaminated. Could the lettuce have caused the problem?
Raccoons were always trying to get the fish but didn’t seemed to have any success. Could they have introduced a disease?
Maybe there was a fish-borne disease? But no new fish had been introduced for months.