if the tank is made from thin glass then it will be more likely to bow near the top in the middle. You could glue a support strap across the top if you are really worried but it should be ok.
What is it made out of? If it's a 10 gallon I'm guessing it could be a plastic tank and not glass. A 10 gallon glass tank is unlikely to bow unless it's very thin glass. If it's plastic I'd say it'd be OK as there is a certain amount of elasticity.
i can see the bowing by looking at how the hood meets with the edge of the tank. It seems to be made of glass, but it should have shattered if it bowed. so maybe it is plastic. Either way I think ill make a brace.
glass has some flexibility and glass tanks can bow if they are made from thin glass or don't have support straps. If the tank is made from 4mm glass then it might bulge/ bow outwards at the top a couple of mm when the tank is full. If the tank is made from 5 or 6mm glass then it shouldn't bow but 5 & 6mm glass will cost a lot more and small tanks are usually made from 4mm.
If the tank is made from 3mm then take it back and get one made from 4mm.
It also depends on how high tha tank is. Up to 12 inches high and 4mm glass is fine. If you go to 15 or 18inches high then you want thicker glass to reduce the flexing in it.