top of page

Culturing Live Phytoplankton

Microalgae is the base of the food chain and crucial to the captive breeding process.
    This is a simple guide to culturing your own live phytoplankton.  Live phytoplankton is useful if you are using the "Greenwater" technique for raising larval fishes.  It can also be used to feed rotifer cultures.

Things you'll need:

  • Live Phytoplankton Starter culture (You can get starter cultures from various sources such as Florida Aqua Farms, Reed Mariculture or even a local hobbyist)
  • Flexible Airline tubing
  • Rigid Airline tubing
  • Air pump
  • Culture containers (2L soda bottles work great. Drill a hole in the cap to accommodate the rigid airline tubing.  Collect some extra caps that remain undrilled.)
  • Fertilizer (Some people use Miracle-Gro but I prefer Guillards F/2 solution from Florida Aqua Farms.)
  • Clean culture medium (Saltwater with a specfic gravity of 1.015 with fertilizer added as per instructions.)
  • Light (a simple shop light or aquarium fixture is fine.)
  • Airline gang valves
  • Ordinary, household, 5.5% bleach
  • Dechlorinator (Some people use sodium thiosulfate for this, I use ClorAm-X.)
  • Funnel
  • Plastic Bottle "crate" (The type that the soda bottles arrive at the store in.  I got mine from a local party store for free by simply asking. These work great for holding the bottles... I've seen many people make elaborate contraptions to hold the bottles, these are perfect since that is what they were made for.)

                                                       Getting Started:

Sterilize the 2L bottles with bleach and dechlorinate.

If you are using a commercially available starter culture simply follow the directions provided.

If you are starting with a culture from a local hobbyist pour the culture into a 2L bottle and add culture medium until you achieve a light green color.

Insert a rigid airline through the hole in the cap, attach to a pump via flex airline and a valve, and start the air  flow, not too much.  Leave the cap on loosely so air can escape from the bottle.
Set in front of the light and wait a week.


The culture will get darker, and in about a week's time, you will have a nice dense culture that can then be propagated by pouring a third of it into a prepared bottle as above. The two thirds remaining can be used to feed your pods, clams, filter feeders, brine shrimp, rotifers, or fish larvae (via the rotifers). More often, I split the dense culture in half by pouring half of the dense culture into a fresh bottle and refilling both bottles with the culture medium and starting over.  I do this because I can't use 2/3 of the concentrate fast enough and it also makes for a shorter time for the culture to mature.

About non-live phytoplankton preparations:


Concentrated, "non-live" phytoplankton or "Instant Algae", can be purchased economically, and has many advantages over home grown live phytoplankton in some applications. For some breeders, live phyto is completely unnecessary, and they rely on purchased concentrated microalgae. For more details on both types of phytoplankton, see the next page.

                                          Suppliers of live cultures, culturing supplies, and concentrated phytoplankton:



bottom of page