How to Grow Rotifers

What are rotifers?

Rotifers are small multi-cellular animals that range in size from 40 microns to 2000 microns. There are about 2200 species of rotifers, most of them are found in freshwater and only a few species are found in saltwater.

Brachionus plicatilis with resting egg (photograph by Jung Min-Min)


The species of rotifers I grow and will be discussing is L Type - Brachionus plicatilis, commonly called L-Type rotifers. They are the most common rotifer used in the saltwater hobby for raising larval fish. L-Type rotifers are 200-360 microns in length and are the ideal size for most larval fish, seahorses and are also a great food for SPS and LPS corals.

Gallery of Rotifers


How to culture rotifers

Rotifers have a bad reputation for being hard to grow. That rumor is farthest from the truth - they are probably the easiest thing to grow next to algae! Here's the list of equipment you will need to grow your own rotifers.

1. A clean 5g bucket (white works best)
2. An air pump, air hose and air bubblier
3. Saltwater (1.018sg - 1.019 is best)
4. Rotifer food - phytoplankton

You do not need a heater or a light. And you do NOT need to grow your own phytoplankton for rotifer food. I highly recommend buying the phyto - growing it is a lot more labor intensive and difficult than growing the rotifers themselves. I buy an extremely dense phyto concentrate (around 70 billion cells per ml) and dilute this down to about 18 billion cells per ml. It's cheap, you only use a few drops twice a day, and you can freeze it so it lasts a long time.

Phytoplankton
The best type of food for L-type rotifers is Nannochloropsis phytoplankton. I buy Nannochloropsis in a very dense concentrate and dilute it about 3 to 1 with RO. I fill up 1/2-L bottles with this mix and freeze them until I need them. A single L-type rotifer can eat about 115,000 cells of Nannochloropsis each day. This sounds like a lot, and it is, but this algae concentrate is at a density of 18 billion cells per ml. (Reed Mariculture is a good source for phyto too!)

Nannochloropsis concentrate



Getting started
Now that you have your equipment you're ready to grow the culture.

Step 1:Order live rotifers. (Reed Mariculture is great for this: Reed Mariculture / Marine Larviculture Feeds & Aquarium Products)
Note: You can use resting cysts but it's more difficult to get a culture started, and most live cultures are dense enough that all you need to do is add water and you are up and running.

Step 2: Find an out-of-the-way space in your home where the temperature stays moderately warm. The ideal temperature for the fastest reproduction of rotifers is 80f, but they will grow and reproduce just fine at temps above and below 80 too. I have my culture in the basement where the temp is about 75 in the summer and down to 70 or lower in the winter, and the rotifers do great all year. Lower temps just mean the rotifers will reproduce at a slower rate. But even at a slower rate they reproduce extremely fast!

Step 3: Setup your bucket, air pump and air stone and fill the bucket with 3-1/2 to 4 gallons of salt water mixed to 1.018sg-1.019sg. (Note: We use a 30g Brute trash can to house our saltwater for the rotifers). When you get your live culture place the unopened bag in the bucket and let the temp of the rotifers slowly match that of the bucket. After about 20 minutes the temp should be fine and you can open the bag and let them loose. Adjust your air stone to a light to medium bubble rate. You don't want the bubbles to be too strong, just enough to keep the water aerated and moving around.




Step 4: Feed the rotifers. Add a few drops of phyto until the culture water has a very light green tint. The amount you feed will depend on how dense of a culture you keep. I keep my culture between 50 to 100 rotifers per milliliter and I need to add between 6 an 12 drops (depending on the density of your phyto) twice a day to keep the culture water at this light green tint. If your color is darker than it should be at second feeding than skip that feeding. Below is a chart to help you with the ideal color - you're shooting for a color right in the middle (a lighter than the second bar but a tad darker than the third bar).



Harvesting Rotifers

Rotifers are only nutritious if there bellies are full so if your culture water isn't a light green tint at the time you want to harvest you should feed them more algae and wait a few hours for them to eat before harvesting them.

It's extremely important to harvest 25% to 30% of your culture everyday and replace with fresh saltwater mixed at 1.018sg-1.019sg. One rotifer will turn into thousands in one week so you need to harvest to keep a healthy culture. When I don't need the rotifers for clown fish larva I add them directly to my reef system - the corals love 'em!
Note: Your culture should still be safe if you skip a couple of days every now and then.

Managing Ammonia
You will need to periodically test your culture for ammonia levels. A standard ammonia test kit works fine. If you find elevated ammonia levels you need to add a product like CHLORAM-X per directions on the bottle.
Elevated ammonia levels = dead rotifers.

Weekly Container Cleaning
To ensure a healthy culture, you need to keep the culture clean of debris build-up. Algae will eventually build up on the sides and bottom of the culture container, and other debris will collect at the bottom. If you are using a 5g container for your culture, then this cleaning is easy:

• Turn off the bubbler; wait 20 minutes for all to settle to the bottom
• Clean out another 5g container
• Gently poor the rotifer culture into the clean bucket - leaving all the debris in the old container

If you are not using 5g buckets, then you can clean the sides with a sponge and then turn off the bubbler. Wait 20 minutes for all to settle. Siphon out all the debris from the bottom of the container.

Summary
Growing rotifers is easy. If you follow the steps, feed them and harvest them everyday then within 2-4 weeks you'll have a healthy and dense culture ready for feeding to larvae and also your corals!

The reasons cultures crash:
1) Under/Over-feeding
2) Not harvesting
3) High ammonia levels

So you can see it's pretty easy to grow rotifers with just a little bit of time - and a little extra cash for salt and food!

Sustainability Tip:
If you plan on growing rotifer cultures for raising fish, I would highly recommend that you keep at least two continual cultures going at the same time. It's much easier to maintain cultures than it is to start them. To do this, instead of throwing out or adding the harvested rotifers to your tanks, just use them to start a new one. Then repeat the steps above to create a second healthy and robust culture. Just be sure that the harvest you're using is from a densely populated culture. (We regularly maintain three rotifer cultures).

Excellent guide Barb!

I'm actually really relieved to know that you've had success maintaining these cultures with this method versus the headache outlined by Joyce Wilkerson and others. I might hit you up for 1 single rotifer in a couple of months.

We went through the on-line info on how the raise them and it is way too complicated. They really are about the easiest things to grow. When ever you want some let us know and we will get you started.

Originally Posted by Reef Clowns Aquaculture

Excellent guide Barb!

I'm actually really relieved to know that you've had success maintaining these cultures with this method versus the headache outlined by Joyce Wilkerson and others. I might hit you up for 1 single rotifer in a couple of months.

You are so right...initial research scared the begeemas out of me...you should've seen what we went thru with our first attempt - which followed Joyce's and others recommendations...it was so frustrating

Then I talked with Randy Reed and decided to take the easy approach...piece of cake!
I'm happy to get 'ya started in a couple of months just let me know!

Great post Barb

Thanks for this, Monica and I are looking forward to getting started, well I am.

I'm excited for 'ya! If you have any questions along the way just ask! (Make sure you use white or clear buckets...need to add that to the guide)

Great thread Barb!

Are you guys growing Rotifers again??

Yes we are. The cultures are almost back up to full density. Took a lot longer to get them going again then expected but they are going.

I let mine crash. theres no point in dealing with 5 cultures. Im not dumping them though. Maybe i will get lucky and start them up again with the cysts.

Thats all we did D. We just emptied all the water (almost all) but left the crud and added clean water, phyto and they came back.

I bought a book on growing Rotifers online the other day. I was just curious to learn a little more about them.

One thing Joyce's book says is that every time a culture crashes, the surviving cysts become more and more resilient. Natural Selection at it's finest!

I'm going to try keeping an extra batch of Rotifers growing outside starting in the Spring.

Never tried growing them outside. I bet it would be easy but also grow mosquitoes.

Originally Posted by chris&barb

Never tried growing them outside. I bet it would be easy but also grow mosquitoes.

And that's bad because?

Our fish and corals will LOVE misquito larvae!

Im sure they would but i dont like getting chewed on when im sipping a brew out back.

Barb,

how do you harvest it mate?? do you use a fine net ??

I dont think mosquito larvae can live in salt water. I would be more worried about airborn pesticides. I have a corn field that buts up to my yard and my luck the farmer sprays his crops

How are the cultures now?

Gday Barb!

purchased a culture and food! express posted to my house should get it by thursday.

will be studying your hread thanks Heaps in advance!!!!!!!

I feel like an idiot !

this is easy ! lol cheers Barb