lol it is not even done yet. It is still in progress. Yeah, I am not too fond of the center brackets either. It will have plywood for sure on top and these won't be all the supports. I made it longer because I was planning on putting shelving space on the sides, however I am not too happy with the length as well. I was looking at some of other stands and I am sorry but maybe my pics aren't showing well enough how each piece is placed and screwed but these other stands it baffles my mind how it can sit on a flat surface and be completely square and hold the appropriate weight without stressing certain sections. It is a little heavy but not that bad.
You have enough supports. That's all you need. It's not how you screw in your supports either. The supports that you do have, are not done correctly. You can put in 50 screws however you like on each support, it still will not support your stand correctly the way it's currently constructed. You don't want your stand falling apart one day, do you? And with 125 gallons of water. You need to look at how other people have constructed. You don't have to follow my advice if you don't want to. After all, it's your tank and your house. It won't be my flood.