I need to acclimate a goldfish from about 68F to 52F. What’s the safest fasted I can go about this?
Background: my aunt and uncle won a carnival fish like 5 years ago, kept it in a 35 gal tank with adequate filtration and it’s been outgrown . They named him Gilbert and got VERY attached. Gilbert is now putting off so much ammonia that they are doing 20% water changes daily and it’s not making a dent. I do not have a tank set up so he’s going in my pond (7k gallons, 9 koi). What’s the best way to tackle this?
I usually acclimate fish over a period of 20-30 minutes. If he's in a bag, easiest way to temp-acclimate is to just float the bag in the water and let it sit for while. If he's coming in a container, I add water from the pond to the container every 5 minutes or so. Take water out, put pond water in until eventually most of the water in the container has been replaced with pond water.
Goldfish and koi are pretty hardy so as long as you get the temps pretty close they should be fine. Another important reason to mix the two water sources gradually is osmotic shock due to different hardness levels. Not really an issue for koi/goldfish in my experience but more delicate tropical fish can certainly be killed instantly due to differences in TDS/hardness.