Right so your going to use the money from the ray pups to pay the bills...
Let's say the rays breed twice a year and drop 5 young, that's 10 a year... Say 8 of those survive to be sellable (i.e. feeding etc no problems)
Sell them at average of £60 a piece.
That's £480, that's about 2-3 months worth of bills with that many tanks, if that.
Then minus off your original setup costs of tanks, insulating garage, filters, and livestock, and you're definetly in negative money
We all have big ideas and plans, but this just isn't viable, wait till you've got the money for something like this.