Keep in mind that water is around 4-5 pounds/gallon. So a 10 gallon tank is at least 40-50 pounds when filled (not including equipment, substrate, fish, light, heater, etc.).
My question, is how heavy is your cat????? If it's heavy enough for you to be scared about it breaking the glass, then that sounds like an incredibly heavy cat...unless its name is Garfield and either you or your partner's name is Jon.
So many fish/plants/inverts to keep, not enough aquaria.