How to Culture Amphipods and Copepods for Your Aquarium

In this guide

Copepods and amphipods, generally lumped together as pods by reef keepers, are tiny crustaceans that form the base of a healthy reef tank's food web. They graze detritus and microalgae, and in turn become a natural, constantly replenishing food source for fish, corals and other filter feeders. Culturing them at home is inexpensive and considerably more reliable than depending entirely on hitchhikers or occasional store bought additions.

Why bother culturing your own

• A steady live food source for fussy eaters, most famously the mandarin fish, which feeds almost exclusively on live pods and often starves in a tank that cannot sustain a natural population.
• A separate culture vessel lets pods breed undisturbed, away from hungry fish, so you always have a reserve to top up the display or refugium rather than depleting a single wild population.
• Pods are genuinely nutritious, high in protein and free amino acids, and feeding them regularly noticeably improves colour and condition in small fish and some corals.

Copepods versus amphipods

Copepods are smaller, often needing a magnifying glass to see clearly, and include both free swimming pelagic species and surface dwelling harpacticoid species that graze rock and glass. Amphipods are larger, more visibly shrimp like, and tend to live among rockwork and macroalgae rather than swimming freely. Both are cultured in broadly the same way, and many home cultures end up with a natural mix of both over time.

Setting up a culture vessel

• A clean plastic container of roughly 2 to 10 litres works well for a home culture, ideally with a lid that has a small hole for airline tubing.
• Fill with pre-mixed saltwater at a salinity around 1.025 specific gravity, made with RO or RO/DI water, never straight tap water.
• Add a gentle air stone or airlift, run low. Pods dislike strong turbulence, so aim for the water surface barely rippling rather than visibly churning.
• A thin layer of fine sand, a small piece of live rock rubble, or a clump of chaetomorpha gives pods somewhere to shelter and graze, and noticeably improves how well a culture establishes.
• A low wattage light nearby encourages a light film of algae to grow in the container, which pods will graze alongside whatever you feed them directly.

Feeding the culture

Pods feed primarily on phytoplankton, microalgae and detritus. Dose a small amount of live or bottled phytoplankton daily, enough to tint the water a faint tea colour, and let that colour fade noticeably before the next dose rather than feeding on a fixed schedule regardless of how quickly it is being consumed. Overfeeding is the most common way a home culture fails, since uneaten phytoplankton fouls the water and crashes oxygen levels faster than an underfed culture ever would.

Starting the culture

• Buy a starter culture of live pods from a specialist supplier or a well regarded local marine store, rather than trying to build a culture solely from hitchhikers, which takes far longer to reach a usable density.
• Acclimate the starter culture gently to your container's water, the same way you would acclimate a new fish, before releasing them in.
• Expect four to six weeks before the culture is dense enough to begin regular harvesting. A jar that looks empty for the first couple of weeks is normal, not a failure.

Harvesting

• Once the culture looks visibly dense, pour a portion through a fine mesh sieve, roughly 55 microns, which catches the pods while culture water passes through.
• Rinse the sieve gently with clean saltwater, then tip the harvested pods directly into your display tank, sump or refugium.
• Always replace whatever volume you remove with freshly mixed saltwater at matching temperature and salinity, so the remaining culture is not left in a smaller, more concentrated volume.
• Harvest modestly and regularly rather than emptying the whole culture at once, so breeding adults are always left behind to rebuild the population.

Keeping the culture healthy long term

• Do a partial water change every week or two, since a culture running for months slowly accumulates waste even with careful feeding.
• Keep a simple log of feeding dates and how quickly the water clears, which makes it much easier to spot a culture that is drifting toward overfeeding or starvation before it actually crashes.
• Watch for warning signs of a failing culture: a sudden foul smell, persistent cloudiness that does not clear, or a growing number of dead pods on the bottom. If this happens, cut back feeding immediately, do a partial water change, and harvest any surviving pods into a fresh container rather than trying to save the existing one.

A note for Indian hobbyists

Live starter cultures and specialist copepod phytoplankton blends are mostly available through online marine retailers rather than general local fish shops, so factor in shipping time when planning a first culture, particularly during the hottest months when live cultures travel less well. Once an established culture is running well, it is easy to share a portion with other local reefers, which is how many Indian hobbyists actually get their first starter culture rather than buying one directly.

Article content © Ravi Teja. All rights reserved.