How to Create A Healthy Marine Ecosystem with Pods - A Buyer's Guide To Copepods
Pods are the unsung heroes of a saltwater aquarium and hobbyists have only recently been singing their praises. These tiny crustaceans consume detritus, bacteria, algae, plankton, dinoflagellates, and even diatoms, then transfer the acquired nutrients to consumers like fish and other predators higher up in the food chain. What that means for aquarists is you are not only harboring a community of animals that help you keep the tank clean and fend off pests but your also supplying a very natural, nutrient-rich source of food for your fish and corals.
During our very own BRStv Investigates Biome Series, we found that adding pods to new aquariums was one of the most beneficial defenses against the ugly stage.
What are "Pods"
The term "pods" is a generic term, primarily used in the aquarium hobby, that refers to a variety of copepods and amphipods that can grow in saltwater aquariums. Pods have classically found their way into our aquariums as hitchhikers but you can also purposefully introduce them into your aquarium. Companies like Algaebarn and Reef Nutrition culture pods in captivity and offer a variety of different species for sale.
Photo credit: Algaebarn
Pods will eat a variety of single-celled organisms, microalgae, phytoplankton, and decaying organic matter in our aquariums which makes them a critical part of the natural clean-up crew we rely upon to maintain a stable ecosystem. While the preferred diet of a particular pod species is very species-specific and changes with various life stages, they are opportunistic and will eat what is most abundant or available to them.
Pods inhabit the substrate, live amongst macroalgae, and will suspend in the water column. You don't have to have a refugium to maintain a healthy population of pods but having a safe haven for the pods to propagate safely away from predators certainly helps ensure their abundance. For the most part, fish and other animals in your tank will capture and prey upon pods as they naturally would.
The water flow through your refugium will distribute the pods throughout your display or you can use something like the Pod Hotel to help purposeful transfer pods from the refugium or sump. Even taking a small clump of macroalgae from the refugium and gently washing it in your display will distribute pods.
Amphipods vs Copepods
While we use the generic term "pods" to refer to all of these tiny crustaceans in our saltwater aquariums, there really is a multitude of individual species that belong to two different sub-groups.
- Copepods: Smaller in physical size compared to amphipods, adults typically measure no larger than 2mm long.
- Amphipods: Larger in physical size compared to copepods, adults can grow up to +/-300mm long.
While copepods and amphipods are similar ecologically, there are morphological differences and competition that can arise between them in an aquarium. Being larger, adult amphipods are more voracious and will actually prey upon smaller copepods, especially the microalgae and planktonic feeding larval copepods. Amphipods will also consume larger particles of detritus but also feed upon bacteria which can compete with benthic species of copepods that prefer the same source of nutrients.
Copepods and amphipods can exist side by side in your aquarium and both will ultimately provide the same if not similar benefits. Achieving self-sustaining populations is possible by providing refuge for copepods, periodically adding more copepods to the aquarium, and dosing live phytoplankton.
Photo credit: Algaebarn
What Pods Should I Buy?
Most experts would agree that a variety of species in your aquarium will result in the maximum benefit. The mix of species will fill different niches and consume different things, all the while providing a variety of nutrients for your fish and corals. This is exactly why the blended cultures of copepods from Algaebarn are the most popular choice for introducing pods into your aquarium for the first time.
Think about the feeding habits of the fish and other animals in your aquarium and choose a blend that will best suit their needs. What do the pods prefer to consume and where do they reside in the aquarium? From here, you can make a more educated decision about which pods are best. For example, if you have a Mandarin Dragonet, you will want to choose pods that inhabit the substrate where the Mandarins like to hunt.
All of the Algaebarn copepod cultures are free of pests and contain a variety of pods at different life stages, from juveniles to adults. The various life stages help the pods to more efficiently establish a self-sustaining population in your aquarium.
- Tigriopus californicus: Loaded with amino and omega-3 fatty acids, Tigriopus copepods make a nutritious meal for even the pickiest of fishes. These pods occasionally inhabit the water column and make quick bursts of movement as they "Swim" which makes them an easy target for your critters. Females can lay hundreds of eggs during their lifecycle. These harpacticoids contribute to your clean-up crew by consuming detritus and nuisance alga.
- Tisbe biminiensis: Small and hardy, these harpacticoid copepods tend to inhabit the cracks and crevasses of live rock and macroalgae. Their secretive nature helps them to maintain lasting populations in marine aquaria. Like the above, Tisbe copepods add to your clean-up crew by consuming detritus, phytoplankton, and invasive algae in your aquarium; think of these guys as the smallest big mouths in your food chain.
- Apocyclops panamensis: Being slightly larger than Tisbe and slightly smaller than Tigriopus, these resilient copepods round out your tank's zooplankton size range. Apocyclops is extremely nutritious with a very high amino acid and protein content. It reproduces quickly by laying eggs every 4-6 days--about twice the rate of Tisbe and Tigriopus! This cyclopoid spends much time in the water column, providing a continuous source of nutrition for seahorses, swallowtail angelfish, etc.
- Oithona colcarva: This highly adaptable pod is a cyclopoid like Apocyclops but spends even more time in the water column. Oithona also feeds on smaller particles, consuming suspended items as minute as bacteria. Its nocturnal nature helps to prevent it from being completely decimated by hungry zooplanktivores.
- Euterpina acutifrons: Hailing from the order Harpacticoida, the coastal dwelling Euterpina acutifrons is a non-selective herbivore loaded with a variety of proteins and amino acids that are perfect for bolstering the health and longevity of fish and corals.
Blended Copepod Cultures
Contains Tigriopus & Tisbee Copepods.
Great snack for Mandarin Dragonets and other substrate-hunting fish
Contains Tisbe, Tigriopus, and Apocyclops
A perfect blend for both substrate hunting (Mandarins) and suspension-feeding fish like Anthias
Contains Tisbe, Tigriopus, Apocyclops, and Oithona
A diverse blend for all of your fish and corals
Contains Tisbe, Tigriopus, Apocyclops, Oithona, and Euterpinah
The most diverse blend that will feed your entire reef and help to reduce the spread of nuisance algae
Single Species Copepod Cultures
Single species pods are great for boosting the populations in an existing aquarium or when you have a specific fish or animal that will benefit from this type of pod in the aquarium.
How To Introduce Copepods Into Your Aquarium
Pods are best introduced into your aquarium before the tank has been heavily stocked with fish and other animals that can prey upon them. In fact, adding pods just after your tank has cycled can be very beneficial in the maturation process of your aquarium and help fend off some of the common pests we encounter through the "ugly stage". That said, you can add pods to your aquarium at any time and still benefit.
- It is best to introduce pods at night when the fish and other animals are less active and less likely to prey upon them right away.
- Temperature acclimate the pods by floating the jar in your aquarium for 10 minutes.
- Turn off your return pump and filtration, then reduce flow via powerheads to allow the pods to settle.
- Pour pods directly into your display or refugium.
- Resume water flow after 30 minutes
Photo credit: Algaebarn
Do I Need to Feed My Copepods?
In an established aquarium, copepods will likely sustain via detritus and bacteria that naturally exist. Supplementing the pods by dosing live phytoplankton in the aquarium increases their nutritional value and will help sustain the population of pods in new aquariums and when attempting to establish a robust population. Live Phytoplankton also feeds corals and other filter-feeding invertebrates in your aquarium so the benefits are multifold so long as you maintain acceptable nitrate and phosphate levels.
Do I Ever Need To Add More Pods?
Inevitably, the diversity and population of copepods will ebb and flow over time based on available resources and predation. Certain species of pods just wind up dominating the aquarium over time. By "boosting" your aquarium with a blend of pods on an annual basis, you can ensure you are maintaining the most diverse biome and, therefore, gaining the maximum benefit from the presence of pods in your tank.