Culturing copepods is one of the more time consuming tasks in the marine aquarium hobby. The fact of the matter is that some fish just cannot be kept without a strong presence of these “pods” making for difficult creatures to keep. This is especially true when breeding fish, as fry will almost certainly be unable to eat the same full sized food their parents can.
For owners who’s fish choose not to eat, copepods can be the solution for the fishes diet. Pods elicit a powerful feeding response, making even the most picky fish dash around searching for more pods to eat. Once the fish is in a feeding mind set, adding in new foods becomes much easier. This makes pods essential to almost any marine tank.
This copepod guide will be directed towards breeders and keepers of difficult to keep fish such as Mandarins. Adding a short boost of pods may be enough to train one or two picky fish, but fry and Mandarins will need a never ending supply of pods. Even the smallest of Mandarins can clean out a tanks pod population in a few days. Without starting your own culture or housing a massive and well aged tank, purchasing copepods will easily eat away at your savings. This makes starting your own culture an essential part of breeding and Mandarin keeping.
What Are Copepods?
Copepods are small crustaceans with over 10,000 different species. They can be found in both fresh and salt water. They can be either free swimming or crawling depending on the species of copepod you choose. For Mandarins we suggest you pick up Tisbe biminiensis.
Tisbe pods, as the are more commonly called, are the easiest pods for most fish to hunt. They crawl across the surfaces in your aquarium, allowing Mandarins an easy chance to look over the area and peck them from the surface. They make for a highly nutritional food source and are one of the easiest pods to culture.
When reproducing pods lay eggs which can float into the water column, making in sump breeding not as consistent as a separate culture. Once the eggs are fertilized they are placed back in the mothers care until they hatch. After hatching their are six stages of growth for pods. Until the 5th stage of growth the pods gender cannot be determined, making younger pods unable to sustain cultures. The complete aging cycle of the copepods is achieved in a short matter of 10-12 days. newborn pods are attracted to lights where as adults hide in substrate from the light. While this does serve to keep the breeders alive in your tank, the light attracted newborns will be eaten by fish before they are able to re-breed, ending the cycle.
While highly nutritious to our fish, copepods do not possess the fatty acids that our fish need. For this reason we use phytoplankton to culture our pods, feeding them a source of fatty acids that will be passed on to our fish. Pods fed through detritus and fish waste have far less nutritional value to our fish.
Now, lets get our culture started.
What You will Need
- A long, airtight container, preferably not see through
- Reverse osmosis water
- Aquarium salt
- Copepod starter culture
- phyto-feast or phytoplankton
- Air pump with air line and air control valve
- 50 micron strainer
- Filter floss
Setting Up Your Copepod Cultures home
First you will want to mix together the water your culture will be using. You do not want to use existing tank water to culture your pods. Our tanks will actually have a number of small life forms living in them, and including these in out culture can either crash or over take the copepods, wasting our time and efforts.
Reverse osmosis water is a strong recommendation but not 100% needed. The culture will be in a small amount of water, making purity very valuable. Unlike our tanks we will not want to be doing water changes to our culture, as this will result in large numbers of the copepods being thrown out. The reverse osmosis process will give you the best foundation for culturing copepods.
The amount of water you will want is about 2/3rds of your containers maximum capacity. This gives you a nice base and a buffer for water parameters. Mix this water in a separate container and leave it there for now. Be sure your salt has completely dissolved before using the water.
Optimal Breeding Temperature:
While copepods can survive anywhere between 21-82 degrees Fahrenheit, the best temperature for culturing pods is 68-77 degrees
For your containers you will want to drill two small holes into the lid of your container. The first will be to supply your culture with oxygen via the air line tubing. You want the tubing to reach all the way to the bottom of the culture to create a full aeration effect and get some water movement. The second hole is simply to allow small amounts of air to move in and out of the container. By covering the second hole with the filter floss you will reduce the outgoing air and help reduce evaporation.
Getting The Culture Started
Now that we have everything in place we can begin the culturing process. First you will want to place your starter culture into the main container. Begin drip acclimation by dripping the new water into the starter cultures container. You can do this by using your airline tubing and control valve. Create a siphon from the new culture water and set the control to only allow a slow drip to go through. Let the water drip into the copepods container until it has tripled in size. The process should take between 20-40 minutes.
With the culture in place you will now give them their first feeding. For phyto-feast fed cultures use only a fed drops into the culture, creating a light clouding effect. If you are using actual phyto then you will want the water to turn a lime green color.
This is a very small amount of water you are feeding. Over feeding can result in a crash, killing off your culture and ending the process. Only feed the pods what they need and do not try to rush through excess nutrients.
For your aeration you can use either an air stone or just the end of your airline tubing. If you are going just the tubing route you will want rigid tubing to keep the tube straight. The water level will be only a few centimeters deep, making a minor curve in the tubing enough to stop the air flow. Next adjust the air flow until 3 bubbles a second are produced. For air stones you will want to adjust your air flow until it creates a small amount of water movement.
With the pods fed, the aeration and filter floss in place and the lid secured you will now be moving your containers into a well lit area. This can be their own personal light of just on the window seal, whatever works best for you.
Congratulations! Your culture has been successfully started.
Maintaining The culture
As your copepods eat their food you will notice the water begins to clear up. You will want to feed them once or twice a day, using how clear the water gets as a gauge for the next feeding. If the water is completely clear you will want to step up the feeding. When the water is still cloudy try dialing the feeding back just a small amount. Eventually you will come to a happy medium of feeding the culture.
As the culture sits the water level will fall due to evaporation. Continue to top off the culture with the reverse osmosis water. This keeps the salinity at the same levels and adds clean water to the system.
Monitor the PH of the culture. Anything above a PH of 9 means you must perform a water change and increase aeration. You can add the removed water to your display tank, provided it is in good enough health to take a small PH hit, to preserve any pods your culture will be losing.
After a months time there will likely be a lot of waste at the bottom of your container. Siphon out 2/3rds of the copepod culture and pass it through your strainer, throwing out the dirty water. Next siphon the remaining 1/3rd of the culture into a temporary container, rinsing off the strained copepods at the same time. Be sure you don’t siphon out the waste too. With their container empty and all the pods now in a temporary home you can clean their main container. Never use cleaning chemicals. Simply hose down the container and wipe it off with paper towels or a new, unused sponge. Any added chemicals or oils from dirty kitchen cloths can impact the culture.
With the culture in it’s small temporary home, create a new batch of reverse osmosis water, matching the salinity and temperature of the existing culture. Place your existing culture back into their main home and begin the drip acclimation process again. Your pods will now have clean water and can continue breeding.
Population Explosions and Collecting
Within one week you will likely see an increase in your cultures activity. New pods have been produced and the culture is actually visible on the sides of their container. Soon after, and sometimes before, the first week you will witness a population explosion. What seemed a small culture will suddenly seem over run with life now as your culture begins to take off. Leave these new pods in the culture for a little while longer.
After ten days the culture should be ready to harvest. Begin a siphon and remove 1/3rd of your culture. Use your strainer to separate the copepods from their water. Add these copepods to your tank and your harvest has been a success.
With a third of the culture now gone you will need to refill the container with a new batch of salt water, matching both the salinity and temperature of the culture. It is recommended you drip acclimate this water as well to prevent shocking your established culture.
Safeguarding Your Hard Work
With the successful harvest complete your pods will be reduced and re-breeding just as when you started the process. Wait another 7-10 days and harvest again, repeating the process.
While this is the exact situation you were hoping for there is one last step we urge you to take. All cultures will crash at some point. After all this hard work it would be a shame to have to re-order your pods and start over. Instead of feeding the first harvest into your tank, place them into a second culture! This will double your production and ensure that only half of your culture can crash at once.
4 thoughts on “How To Culture Copepods”
Thanks for the Copepod husbandry article. I did note that you did not mention any kind of structure for the bottom of the tank or container. Other opinions I have read advocate using gravel, or something like egg crate. Can you comment on this approach? I’ve been using half gallon ball jars without any bottom structure.
Odd that I didn’t mention it in the article. Substrates can give more space for nitrates to stay in and help make tanks last longer. They also give fish more options for hunting for food and digger or burrowing. This is not too important for copepod cultures. A big part of making these cultures is to have at least 2 of them so that when one crashes you can make another. Having to throw out a bunch of substrate when this happens is not ideal. Instead I like to keep it cheaper by going bare bottom like you have been doing.
That’s a good point about using a non see through container. Does enough light get through the container since you mention using light to grow the copepods?
There should be enough light entering the copepods container. They don’t need too much and do well in dim areas.