Wolf3101;1261878; said:You'll no doubt get a lot of conflicting responces to this one but in my opinion you should be fine.

I agree with the conflicting responses for sure, but I would go bigger if you dont already have the tank. IMO a single silver aro should have 200 gallons, and a motoro should have 200 gallons. IMO you could get by with a 300 gallon with a motoro ray and a silver aro, but you would need a great filter and do around 15%-20% water change per week or so. But again, people could argue all day over the correct tank size for an aro, as well as a motoro, so nothing is set in stone concerning tank size. It all really boils down to how you personally feel.