Should you add corals or fish first?


We’ve all asked ourselves which came first, the chicken or the egg, but now that your tank is full of water and live rock, you might be wondering: What’s next? Should I add coral or fish first?

When starting a new saltwater reef tank, you should first stock your tank with fish before moving on to your corals. This will ensure that you’ve had time to get your water parameters stabilized and get some experience before jumping into coral care.

Why fish first?

Let’s be honest, if this is your first tank, you’re just not ready to jump into corals right away. Corals are (often) very expensive and far less forgiving than many fish will be. Hopefully by now you’ve already decided which fish you want in your aquarium anyways so find 1-2 that are considered hardy and go ahead and get them into your tank–just make sure you save any territorial fish on your list to go in last! They’ll feed your nitrogen cycle and start dirtying up the tank for you.

For the first few weeks, just enjoy your fish. Practice doing water changes and measuring your parameters. You might not even have a light capable of growing coral yet anyways so you can take your time and save up for that fancy new LED you’ve got your eye on. Just be sure to take it slow and only add a couple fish at a time. Don’t run out and buy your whole wish list of fish and expect them to survive. That’s a surefire way to overwhelm your biological filtration or to introduce a sick fish that infects the rest of your community.

When can I add coral then?

You should wait until you’ve had at least a few weeks of stable water chemistry. If you test your water once a week and your alkalinity (dKH) and phosphates and such aren’t consistent, then you’re probably not ready. Corals can often survive and thrive in water that isn’t quite perfectly on target, but they struggle with inconsistent water. If their world is constantly changing then they’re just going to get stressed and ultimately die off.

Patience is a virtue in this hobby. Test, wait, and test again. If you think you’re ready, check out your local reef club or local fish store and pick up a cheap frag to get started and see how it does. Just don’t forget to dip.

When should I add a clean up crew?

I suggest you start adding some snails and hermit crabs after your first, but before your corals. There certainly isn’t a shortage of saltwater stores online looking to sell you a “starter” bundle of clean up crew and you may be tempted to buy one of these right away to make sure your take stays clean. These bundles are almost always a bad idea. If you only have 2-3 fish, what on earth are those 30 hermit crabs going to eat? Well, they’re going to eat those 50 snails that came in the bundle!

Consider buying your clean up crew in small batches and alternate them with your fish purchases. Buy a few fish then next week buy a few snails and a couple crabs. Buy a couple more fish then a grab a few more snails. You can certainly buy them together, but I like to alternate because it gives me a reason to go to the fish store again and not leave empty handed!