As you already know, your Fish develop according with the attention that you give him. Until now, you only knew 5 different stages.

For more information about that, visit this link , but now, you have more stages available beyond that 5 ones.

To reach there, first you have to pass thru all stages and have at least 5000 of experience in the 5th stage. Then you will develop to the next level (your Fish becomes grey) and you win 50 thousand Aurux ! Another advantage of reaching these extra stages is that you can make your own store and sell your items.