Definitely try the negotiation tactic. Like some people said we don't know what you were asking for. If you asked for big tanks then they said small try a medium tank. A 55 gallon is a wonderful starter tank. Great way to break into the hobby with some mid sized cichlids and get a feel for breeding them (like convicts maybe since its so easy to breed them). Then upgrade from there once your family sees you are able to handle the responsibility. I remember when I started out my parents only allowed me my one 55 gallon tank until they saw how responsible I was in its upkeep. Then they allowed me more tanks over time. Now I have my own place with my own family and run 8 fish tanks at the same time with a total gallonage of almost 1000 gallons. You will get there with time, but sometimes you start smaller and work your way there. I've been doing this 20 years now and you don't get there in one moment. You get there with time.