Adding another goldfish?

[HooKooDooKu]

I'm currently upgrading my 10 gallon tank with a common and rosie to a 20 gallon. My primary filter will be a Fluval 2, but I also have a Fluval 1 that I could suppliment with.

Would it be too much to add a comet to the mix?

 

[jsoong]

Yes, it will be too much. Common & comets get way too big for even a 20. <Their mature size is 12" or more, and they need room to swim, even if you can somehow manage the bio-load.> I suppose you can keep 2 small ones in a 20 for a while, as long as you have a pond to move them into when they get big.

 

[HooKooDooKu]

I have a next door neighbor and a sister on the other side of town with ponds. My plans all along have been to try to move this fish to one of those ponds once he gets up past about 6 to 8 inches. I'm not going to spend the time or money or floor space for anything much bigger than the 20 gallon to keep a common gold in the house.

As for bio-load, as I said, I've got a Fluval 2 AND a Fluval 1 will cycled filters. The two combined would be equivilant to a filter for a 45 gallon tank (Fluval 1 is for up to 12 gallons, and the Fluval 2 is for up to a 23 gallon filter). The substrait is pool filter sand. I just put the sand and the Fluval 1 filter in the tank to try to do a bit of a fishless cycle of the tank and get some bacteria growing on some of that sand as well as plants as I get them stocked. Shouldn't that be able to handle the bioload for two goldfish upto 6-8 inches in size?

 

[jsoong]

The 20 would be OK up to a point. You'd need to keep monitoring the water parameters to know when you are exceeding the capacity of the tank. I would suspect that you will need to move the fish to the pond once they get to 4"or so.

I would definitely run both filters, and adjust them to get the maximum amount of water movement & surface splashing to maximize O2 exchange. Also, get the smallest fish you can to maximize the time you can keep them inside. <Under good conditions, the commons grow like weeds! >

 

[HooKooDooKu]

...I would definitely run both filters, and adjust them to get the maximum amount of water movement & surface splashing to maximize O2 exchange...

I've already got an air stone going. I did that not so much for surface adjitation but to insure there was always plenty of O2 in the little pocket of space between the water line and the glass top. I also did a small air stone in my 5 gallon eclipse tank that has a betta. Again, just to insure there is plenty of air pumped in under the hood to make sure there is plenty of O2 available for the fish, and plenty of CO2 for the plants.

 

[asudavew]

I have 8 goldfish, one I have had for over 8 years.
They are very, very messy.

They require a tank with a big filter and lots of beneficial bacteria.

They also require big water changes at least once a week, I do about a 90% water change and the nitrate levels are still HIGH!