Coral & Sky

The Ultimate and Easy Beginner’s Guide to Filling Your Tank with Your First Sea Creatures

So it’s now been about a couple weeks since you set up your tank. Now for the fun part, filling it with sea creatures!

Helpful Tools

Before you buy any livestock, there are a few additional small-ticket items to buy:

Bacteria supplement ($)

An inexpensive insurance policy to doubly make sure your tank is livestock ready. These bottles absolutely work and great to throw into your tank when you introduce your first fish.

You don’t want to use this before introducing fish though, because you want your tank to naturally establish a base level of nitrifying bacteria. Adding fish creates a large bump in bio-load, and this supplement helps smooth that transition.

Instant Ocean BIO-Spira

Instant Ocean BIO-Spira

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Turkey Baster ($)

A useful tool for spot feeding corals and fish. Any turkey baster will do, but you’ll probably want one dedicated to your fish tank. I like this one because it has a transparent body so you can see the water level / food particles.

Good Cook 11.5in Turkey Baster

Good Cook 11.5in Turkey Baster

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Glass Algae Scraper ($)

Over time, your glass will get dirty. Snails will help clean, but sometimes you’ll need to clean it yourself. This one is perfect for your IM10 tank because it doesn’t scratch glass and is small enough to clean around corners. It’s also magnetic, which means you move it from the outside and don’t have to get your hands wet either!

Mag-Float Glass Aquarium Cleaner

Mag-Float Glass Aquarium Cleaner

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Cleanup Crew

Buy your cleanup crew. They’re the aquarium cleaning invertebrates that will save you time and money by keeping your tank clean, healthy, and algae-free. We put them in first, along with your fish, because they’re inexpensive and can maintain cleanliness.

Diversity is key for a solid cleanup crew. You don’t want too many, otherwise they’ll starve because your tank will be TOO clean. To start, I recommend two each of: cerith snails, hermit crabs, and nassarius snails. You can add more later if you see algae growth.

There are other cleaners like starfish, shrimp, and emerald crabs, but I wouldn’t recommend them. Starfish typically require larger tank sizes to thrive, shrimps can steal food and damage corals, and emerald crabs can also hurt / kill your other livestock.

Acclimating your cleanup crew

All saltwater livestock require a short adjustment period to reduce the shock of what can be very different water parameters. For the cleanup crew, the most convenient way is to pour the water the cleanup crew came in (usually in a plastic bag from the LFS or online) into a clean bucket (avoid using soap immediately prior), then pour in the same volume of water from your fish tank (~50/50). Wait 15 minutes, then carefully place the critters in your aquarium by hand. Avoid introducing any water from the LFS / online back to your tank as best as you can.

There are other more conservative methods of acclimation such as the “floating bag” and “drip acclimation” methods, but they take a lot longer and are superfluous for most nano reef livestock. Don’t forget, although livestock are sensitive to wild swings to salinity and heat, they are ultimately designed to survive in the ocean -- a turbulent, fluctuating ecosystem in itself!


Buy your fish. You can also do this on the same day as your cleanup crew. A 10-gallon nano reef can comfortably host 2 fish, max. You may see other tanks with more but it’s definitely pushing the limits of your tank. Remember, fish are the main sources of waste and ammonia, which can upset the balance of your reef ecosystem. Additionally, certain species are aggressively territorial towards others.

Please note that the below are general guidelines only; fish can have different personalities and there are always exceptions. Break guidelines at your own risk!

Recommended beginner species

Clownfish (Ocellaris, Percula)


Hugely popular because of the movie Finding Nemo, with plenty of personality. They can thrive as a pair in a nano reef but are territorial, and are generally not compatible with other species. If you go with the clownfish route, make sure to buy both of the same species at the same time, and ensure one is smaller than the other (the larger will become the dominant female, smaller the submissive male).

Gobies (Neon, Coral, Firefish, Clown, Hector’s, Trimma, Yellow, Orange, Green Banded, Shrimp, etc.)


Gobies are generally great starter fish because they stay small, eat diverse foods, and tend to mix well with other species (like Ocellaris Clownfish). They should either be kept singly, or as a mated pair. Avoid mixing multiple different species of gobies.

Some gobies, like the shrimp or watchman goby, tend to live in the sand.

Chromis (blue, green)


Small, hardy, and very aggressive. Their colors will really pop under your blue UV lights. Typically they do better in larger groups more fit for 30+ gallon tanks, but a few together can thrive in a nano. However, they will not co-exist peacefully with clownfish or other damsels in a nano tank.

Basslets (Royal Gramma, Black Cap)


Generally peaceful and striking additions to nano reefs. The Royal Gramma in particular has a beautiful purple and yellow body. They are peaceful to different species but can be aggressive to their own kind.

Acclimating your fish

You can acclimate your fish in the same way as you did with your cleanup crew. Just match the water from your tank with the volume from the bag they come in from the LFS and let them adjust for 15 minutes. Then use a plastic cup to scoop the fish out and pour it into your tank.

Tank Maintenance

Now that you have actual livestock in your aquarium, pour in the entire bottle of nitrifying bacteria.

It’s also time to put in your filter media. Open up the bag of filter floss and cut up small pieces to roughly match the rectangular shape of the basket compartment. Place one or two pieces into the top compartment.

Next, place the Chemi-pure Elite media in the middle chamber, and the Purigen in the bottom chamber. Then place the entire basket into the back chamber of your tank.


You should wait at least a week to see how your tank adjusts to the bioload of your new fish and cleanup crew. Corals are generally more expensive and sensitive to water changes, so that’s why they’re last.

How can you tell if your fish are happy? Just take a look at them and watch for any abnormal behavior. If they’re swimming upside down, unusually lethargic, or not eating, that’s a sign that something’s wrong. Also check your test kits to make sure the water parameters are somewhat stable (salinity, ammonia, and pH are the most likely culprits).

If your fish seem happy and your water parameters check out, then it’s time to buy your first coral! I highly recommend buying your first corals at your LFS instead of online, so you can better gauge color, size, and potential tank placement.

Recommended beginner species

Trumpet Coral (Caulastrea curvata)

Trumpet corals

Shaped like a small trumpet, these corals are a beautiful yet low maintenance species. They commonly exhibit brilliant neon (green, blue, tan) colors and will look amazing under your blue actinic lights.

They don’t require too much light or water flow, and can grow without external feeding via photosynthesis, but they do benefit from spot feeding fish or specialty coral food. It’s fairly peaceful, with very short sweeper tentacles.

Brain Coral (Favites)

Brain corals

One of the most common corals in the world, brain corals are another bright coral which come in a myriad of color tones: green, brown, yellow, cream, orange and red tones.

They require moderate light and flow. They can grow without external feeding via photosynthesis, but they do benefit from spot feeding. It can be aggressive, so a little care is needed to provide it adequate room between it and other non-Favites.

Hammer Coral (Euphyllia ancora)

Hammer corals

Named for its anchor / hammer shaped tentacles, the hammer coral is a fluorescent yet easy coral to start with. It likes to pulse and sway on its own, which really helps accentuate any tank. Its most common colorings are purple tentacles with green tips and green tentacles with pink tips. They also come in the rarer all green, all pink, and orange tentacle varieties.

Hammers are an aggressive coral, and at night its sweeper tentacles can reach a few inches long. Make sure to place them on their own little island in your tank. They are fully photosynthetic but do like to catch meaty foods if you spot feed them.

Micro Lords aka Acans (Micromussa lordhowensis)


A popular beginner coral, they exhibit bright striped color combinations and are more adaptable to various lighting and water conditions. Physically, they are flatter in dimension so they don’t take up too much room -- perfect for nano reefs. They propagate easily, so they are among the most affordable corals as well.

They are highly adaptable, but generally prefer lower light and flow. They can be aggressive, and while I’ve never witnessed it myself, they’re known to extend their stomachs to prey on nearby organisms. Fully photosynthetic, but benefit from meaty foods or other fish/coral formulas.

Mushrooms (Various species)

Mushroom corals

Another popular beginner coral, Mushroom corals come in pretty much every color you can think of. They are extremely hardy and have amazing adaptability to all sorts of lighting and water conditions. They’re typically about 1-2 inches in diameter fully grown and will sometimes contort their shapes from flat to funnels depending on their lighting.

Because of their color variety, they can be used as accent colors to improve the overall aesthetic of your tank. They’re photosynthetic, and also benefit from additional spot feeding; however, a funny downside is that they can thrive too well, and can take over a tank if you’re not careful.

Acclimating coral

Corals are a little bit more sensitive so they require an extra step. You still use the 15 minute half LFS / half tank water method, but with the added step of pouring in an iodine-based solution to kill unwanted pests. I personally use a non-branded Povidone Iodine solution, but Blue Ocean’s Coral Rx dip is also popular among coral owners.

If you go the Povidone Iodine route, just add enough solution to your acclimation tub so that the water turns brown-ish (like tea) and swirl it around. Use your baster and gently flush your corals while they soak.

After the 15 minutes are up, pour out a small amount of tank saltwater in a separate container and rinse off your new corals one last time.

Dynarex Povidone Iodine Prep Solution

Dynarex Povidone Iodine Prep Solution

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Coral placement

Most corals that you buy will come attached to a “frag plug” or a piece of rock. Frag plugs are used because they make it easy to maintain and display individual corals. Your live rock should have plenty of holes where you can insert your corals in.

If they came attached on a rock, you can either put it on your sand bed or glue it on your live rock. However, before you glue anything, make sure you know that the corals will be happy in that location (determined by individual coral flow and lighting needs).

Because frag plugs can have an “unnatural look” until the coral grows big enough to hide it, more advanced hobbyists will detach or cut down the plugs to make the plug less noticeable. This is considered a more advanced technique and not required when you’re starting out, so I won’t go into it, but there are plenty of guides on how to do this online.


Once you’ve got your first corals in your nano reef, you’re well on your way to becoming an expert reefer yourself! Who knew! 😉

The best thing about nano reefs is that general maintenance is very easy. All you need to remember to do is:

  1. Daily RO/DI water addition: Remember, as your tank water evaporates, it leaves behind salt, so you keep salinity in balance by adding RO/DI water. Depending on your region’s humidity / temperature, you might not even need to do this every day. (1 minute)
  2. Weekly water change: Important not just to remove the built-up nitrates, but new saltwater also contains minerals and trace elements which your corals need. (5 minutes)
  3. Weekly filter floss replacement: Just take out and trash the old filter floss and put in another small piece. You’ll notice filter floss turning brown -- this is the bacteria growing from captured organic waste and leftover food. I do this at the same time as my water change. (1 minute)
  4. Feed fish / corals: Pacing is up to you, but beginners almost always overfeed. Every other day is a good pace. Because you only care for at most 2 fish, the food you bought will last you a long time. (5 minutes)
  5. Replace chemical filters: Both Chemipure Elite and Purigen every 3 months. Just buy new ones and trash the old ones. (1 minute)

As your reef progresses and you learn more, you’ll indubitably add more corals, and might even change up your aquascape. You might even start to cut off larger pieces of your first corals and attend coral “frag swaps” with other hobbyists. And farther down the road, you might even decide to take the plunge and buy a much larger aquarium with enough room for larger fish and many more corals!

Good luck, and let me know how your reefing adventures progress! Feel free to share any cool photos or ask me questions at: