If you want to use Rainbowfish as fertilizer, you’ll need to get your Sim’s Fishing skill to Level 6.
Once they’ve reached that level, head to the parks in Willow Creek or Oasis Springs and start fishing. Y
ou don’t necessarily need to use bait to catch Rainbowfish.
For a better chance of finding rare fish, look for sparking fishing signs. These indicate fishing spots where rare fish can be caught.
You can also ask a high-level fisherman to mentor your Sim while they fish. This can help your Sim improve their Fishing skill faster while they’re out catching fish.
Once you’ve caught a Rainbowfish, you can use it as fertilizer to help improve the quality of your plants.
You don’t need a high-quality Rainbowfish either. Even low-quality fish can be used as fertilizer.
If you’re not using the Rainbowfish for your garden, remember that fish will spoil after 24 hours. Keep them in the fridge or a fish tank if you want to preserve them.
Rainbowfish are also useful for completing your Fish Collection, so you may want to keep at least one rather than immediately selling your entire catch.