How to gain more xp on tap fish.
There are a number of ways to maximise XP on Tapfish. They focus on tanks so spend money on tanks if you want more XP.

The XP amounts increase as you level up.

1.  Buying and Selling- Buying fast growing fish (e.g. Green Snapper) this could make up to 600 XP a day for each tank full.  (1 XP per fish purchased [50xp] 2xp for ever fish sold [100xp] every 4 hours) You will want to mass sell these fish.

2. Feeding -If you buy a fish then feed it, then buy the next fish and then feed it. You get 1xp per fish fed so up to 50xp per tank of new fish. This method can be tiring...

3. Welcome Back- You get 2xp when you simply check your tank.

4. Love- You get 2xp every 3 hours per tank when you Love your fish.

5. Cleaning- You get xp dependent on how much cleaning the tank needs, around 1-3xp.

This means you can make a possible 988xp per tank per day (On Level 14)