gremlin

Put a bit of gravel in the bottom of the net to help it stay open. I've done that with a fish I wanted to watch for injury reasons. You would still have to figure out how to keep the shark from jumping out - maybe a piece of cardboard or something.

Do you have a plastic jug of milk (or juice or whatever)? Or an gallon (litre) sized water jug? If so, you could rinse it really really good and use an ice pick or nail to make holes in it and float that in the tank.

Or you could use a pot lined with a plastic bag and wrap towels or a blanket around it to help keep the water at a stable temp. Then when you do the daily water changes, use water that is a tad bit warmer than the water in the container to help warm it up. Putting the lid on would be okay, just use a piece of tubing or a rolled up piece of paper hooked over the edge of the pot to keep the lid from clamping on too tight. That way air will still get in. If you have an air pump and a divider, maybe put one of the hoses into the pot with the shark so there are bubbles for the air.

gazz2005uk

Thanks, i think i will try the milk carton idea.

I have him in a net at the top of the tank at the moment as I am not at home. Its not ideal as the net isn't very big but i think he should be ok for a while.

Also, the jumping out is not a problem as I have put the lid on the tank