My Aquarium
11 Achievements
1-2h
My Aquarium Master
Unlocked all fish.
10.5%
How to unlock the My Aquarium Master achievement in My Aquarium - Definitive Guide
Alternatively, you can just load the game up every few days. I did it this for 2 months and still had 12 fish left to unlock, so doing it this way will take a long time.
You can tell how many fish you have yet to unlock by looking for any tabs with ??? in the Add Fish section of the Aqua Center, but there is no way of knowing how long you will need to wait to unlock each fish.
Please vote positively if this guide was helpful and feel free to leave a comment if I can improve it in any way.
The way you unlock fish is by breeding, playing the game for periods of time and advancing the system date as a few unlock every couple days. There is a total of 58 total fish, but you only need 51 of them to unlock the trophy.
Easiest way to get this is to do the method mentioned in Breeding Master first, then make sure the game saves, quit the game again, advance time by one full year and restart the game. Once the game loads, you'll unlock an insane amount of fish right off the bat and should be enough to get you the trophy! If you do not get this, you will need to delete your saved data and go through the method again (seems it occasionally won't unlock enough fish this way and won't unlock anymore after that).
Moreover, if you continue to look through aquariums, constantly moving from one to another, then you will never end the breeding process. Actually, I didn't check if lyon is infinite because after the 3rd time I got tired of it)