Fishdom is free to play, though certain in-game elements can be purchased for real money. To avoid accidental in-app purchases, just adjust your device settings.

1. Open the Play Store app.
2. Tap the Menu icon and select Settings.
3. Tap Require authentication for purchases.
4. Select one of the authentication options.
5. For all purchases through Google Play on this device. Authentication will be required for all Google Play purchases (including in-app purchases).
6. Every 30 minutes. The system will request the password for Google Play purchases every 30 minutes. Just note that once you enter a password all purchases made over the following 30 minutes will not need a password.
7. Follow the instructions on the screen.

For Kindle devices:
1. Open the Amazon Appstore application.
2. Go to Menu -> Settings.
3. Untick the In-app Purchasing option.