Collecting Plankton for Marine and Freshwater Fishes and Invertebrates

Hello, Frank Indiviglio here. Plankton forms the base of the food chains in all the world’s fresh and marine waters. Comprised of innumerable species of tiny, often microscopic plants and animals, plankton is a very useful but overlooked food source for tiny fish fry, filter-feeding invertebrates and seahorses, pipefishes and other small live food specialists.

Collecting Plankton

Marine waters are undoubtedly the best sources of plankton for seahorses and such creatures, but do not hesitate to try fresh water plankton as well. Just bear in mind that fresh water creatures will perish rapidly in salt water, so don’t overload your tank.

Available through biological supply houses, plankton nets are the most effective means of harvesting this valuable food. Don’t forget to examine your catch with a hand lens or microscope – you won’t believe your eyes!

Using Plankton

When rearing Atlantic seahorse fry at the Staten Island Zoo, I often towed a plankton net behind a boat and by hand from a dock. My efforts were rewarded with an amorphous glob of “organic material”, but the seahorses sure knew what to do with it!  Their reactions were much more vigorous than when presented with their standard meal of brine shrimp, and they grew rapidly.  I have also noticed that northern pipefishes immediately begin feeding when fresh seawater is added to their aquarium…I usually cannot see anything that looks like food, but they do!

I consider plankton to be nearly indispensible for seahorse and pipefish fry, and for adult dwarf seahorses and similar species. But nearly all small fishes and invertebrates, including fresh water species, will eagerly accept plankton as well.  Its use will greatly improve your chances of success with a number of delicate organisms.

Useful Products

Fortunately, “plankton substitutes” are available for those unable to collect their own. “Reef Bugs” are living microbes that are eagerly accepted by corals and other invertebrates. A wide range of other foods for filter feeding invertebrates helps simplify the keeping of these fascinating creatures.

Newly hatched brine shrimp, while not a complete diet for seahorses and pipe fishes, may be nutritionally improved through the use of Artemia food.

Further Reading

The Monterey Bay Aquarium has posted an interesting article on plankton collecting here.

Please write in with your questions and comments.