Cold Problems

Hi all,

This winter has been hard on my aquarium. It currently houses two 5-6" feeder goldfish, and one 5" common plecostomus. It's a 30 gallon tank with a 15 gallon planted sump. The room in my house where the fish are kept has been around 55 degrees F for a couple of weeks, as the outside temperatures haven't been above freezing in a while. The room can't simply be made warmer, as there is no heater in there.

A few weeks ago, I put a heater in the aquarium on the lowest setting. My tank was so cold that it stayed on constantly and warmed things up too quickly for my juvenile bristlenose plecostomus, who died from what I assume was shock. I removed the heater after this happened. Fast forward to today, and I see my big, four year old Common on his back (still breathing). Needless to say, he's probably a goner. The tank temperature is around 53 degrees F. I understand that plecostomus catfish are warmwater fish, but this particular one has gone through three winters like this previously without an issue.

The goldfish still seem healthy and active. Is there anything I can do for my plecostomus? Is he likely to snap out of his upside down nap if I warm the tank up again? In the event that my plecostomus dies, what other fish that are more tolerant of cold water can replace his job of being a janitor?

Thanks!

Thanks for the advice. I'm going to test my heater in a 5 gallon bucket overnight to see where it stabilizes at the lowest setting. If it's within goldfish range, I'll gradually bring the tank temperature up with water changes and throw the heater in the sump.

Left overnight at the lowest setting, the bucket warmed up to 70 degrees and stayed there. That sounds about like the sweet spot for goldfish, and a plecostomus. Sadly, my pleco didn't live through the night. I'm currently warming up the tank (slowly) with the heater by plugging it in and unplugging it. 2-3* per day should be safe, right?

A 200 watt heater is a tad bit inappropriate for my setup, but will be good for the 90 gallon tank I'll be moving in to in a few weeks. Once that's set up, I'll get a pair of plecos to resume janitorial duties.

Also, I've noticed that my goldfish slow down a bit with the colder temperatures. Can that be attributed to their metabolisms preparing for hibernation? I've seen goldfish ponds with thick ice over them in the winter, only to have the fish miraculously come back to life in the springtime. Hardy fishes, they are.