Here’s the dilly-o: I have a single fantail, aged approx. two years (that I’m aware of) living in a ten gallon tank. Since I bought her in mid-2007, I’ve given her weekly three-gallon water changes and kept the tank filtered. I’ve wiped down the sides of the tank while doing the water changes, but I’ve never emptied the tank to clean it thoroughly. In fact, she hasn’t been removed from the tank since the day she went in. There’s a nice algae population in the bio-filter doohickey, but I keep it off of everything else. She seems perfectly happy with this arrangement; she’s an active, healthy looking fish with as much personality as a fish can have.
I’ve recently come into possession of an aerator, and I’m thinking of sticking it in there because, well, why not? It can’t hurt… or can it?
I’m very concerned about upsetting the ecology in there. Have I been flirting with disaster by not having an aerator this whole time? I change a third of the tank every week; that seems to be keeping the fish healthy. If she were going to suffocate it seems like she would have done it by now. I’m worried about an increase in the oxygen concentration causing an algae bloom, or ick, or some other problem.
On a similar note, being that she’s a bottom feeder and after two years I can’t find a single visible speck of gunk in the gravel, is it safe to assume that I can carry on this cleaning (or lack thereof) arrangement forever? It would seem that the filter is picking up all the poops. I’m very reluctant to even stick a sucker in there to clean the bottom, for fear of dredging up some sort of Lovecraftian fish-poop death cloud. Aside from her midnight rock-sucking, it’s been undisturbed for almost two years.
What to do?
If you’re doing frequent water changes, you should be able to have some idea if the filter’s picking up enough: when you put the clean water in quickly, does anything cloud up under the stream of clean water? Mine does to a degree, even though the gravel looks clean. If a lot is stirred up by adding something to the tank, it should be sucked up within an hour or so if you’ve got a clean pad in your cleaned filter. Tip: don’t remove the pad without turning off the filter first. I learned the hard way what a mess that makes.
I’m a little surprised that you have a healthy fish after two years of no aerator - you very likely wouldn’t without those water changes. Goldfish have high oxygen requirements. I would definitely put in an air stone. My goldfish has a 4" stone and one of those little ones (the second one only because there are two outlets on the airpump, and it’s less noisy than blocking one).
[[Lovecraftian fish-poop death cloud]] I love that band!
What kind of filter are you using? Is it one of those bio-wheel type things? That should be enough - together with the water changes - for a goldfish. When you do the water changes, it’s good to siphon the gravel.
If your goldfish shows any sign of disease, the first remedy to try is addition of some iodine-free salt to the tank. Make sure it’s iodine-free. Goldfish like slightly brackish water and salt often takes care of problems that arise.
I kept my goldfish in a ten gallon aquarium for a few years. When he got too big, I put him in a whiskey barrel with a plastic liner outside. He’s doing great.
Agitation at the surface of the water is what aerates it. An air stone wont add anything more than a little more surface agitation, but not that much.
Algae eating “sucker fish,” Plecostomus, or otocinclus are tropical and wont be happy with a cold water species like a goldfish. Some plecs get huge anyway.
You don’t ever want to do a total water change as you will disrupt your already established nitrogen cycle. If you wanted to make a change, you could move up in tank size. Most Goldfish need 10g of water minimum, and a 10g tank with substrate, decorations, rocks and such obviously wont hold 10g of water.
Sounds like you are doing everything right by your fish.
I’ve never noticed any particulate stuff churning up as I add water, but I’ll keep an eye out. For filtration, I use one of those hang-outside-the-tank dooflunchies that sucks the water up through a tube, runs it through a screen full of algae, then a carbon filter, and then dumps it back in the tank.
One thing I have been careful to do is keep the water level about an inch below the output of the filter, so that it falls through a bit of open air and upsets the surface. This generates a little stream of bubbles that descend about halfway down the tank before their momentum peters out and they rise to the surface. I guess that contributes to the oxygenation.