Unsure Of Tank Is Under-aerated

Hi,

I've just got two fantail goldfish, Bill & Bob, from a previous owner, and have been trying to read up as much as I can on how to best look after them. I am concerned that there might not be enough oxygen in the water.

They are both 2 inches long. I have them in a 45 L (10 gallon) tank, with a filter that has an output of 600L/h. There are also 3 live plants (not sure what type) in the tank. There are also two shrimp that came with them, the previous owner didn't know what type they were. I've done some research and think they may be ghost shrimp. I replace roughly 10 liters from the tank every 4 days.

They spend their time when inactive at the water surface and it's not uncommon for them to gulp the top of the water. Is this a sign that they are not getting enough oxygen in their water? What could I do to increase the oxygen content beyond what I'm currently doing? I got them second hand with the current tank, which I know I'll have to upgrade to a bigger one in time. But I thought it would be sufficient for now for the two of them as they are still quite small?

Any suggestions?

I would also get the water tested as gulping at the top can be a sign of ammonia and/or nitrite in the water. If you don't have your own test kit (having one is advisable) take a sample to a fish shop and ask them to test it - but get them to write down the numbers not say something like a bit high or OK as fish shop workers are known to say things are OK when they are not. The only acceptable value for ammonia and nitrite is zero.

When you got the fish did you also get the tank and filter or is it a brand new tank and filter? The reason I ask is because if the filter in particular was new, you are now doing a fishless cycle. If this is the case, can I suggest you read this which explains what you need to do.




And I hate to tell you, but you need a bigger tank and fairly quickly. Goldfish grow huge - fancy ones like yours grow anything up a foot long. The minimum tank size for fancy goldfish is 20 American gallons for the first and 10 for each extra one so you need 30 US galls for your two, that's 115 litres at the minimum.