This is really cool by the way, my sister and I have made posts about the need to encourage the idea of 'levelling' in Steem, this is a concrete effort in making that a reality.

Some more feedback:

There are many steps between the starting account level (25 Steem I think, about 50,000 VESTS) and the smallest dolphin (4798 Steem, 10,000,000 VESTS). More granular steps in between "Minnow" and "Dolphin" would make a sense of achievement/growth possible for ordinary users who don't have hundreds of dollars to spend or whose posts don't make the trending page. Thresholds at 100,000 VESTS and 1,000,000 VESTS would achieve that I think. I'm not sure what they should be called, but I guess some kind of medium sized fish.

<100,000 VESTS = Minnow
>100,000 VESTS = Medium fish? = About $8 at current prices
>1,000,000 VESTS = Large fish? = About $80 at current prices, certainly a meaningful milestone for many users
>10,000,000 VESTS = Dolphin = About $800
>100,000,000 VESTS = Orca
>1,000,000,000 VESTS = Whale

Just my thoughts!