The Purple Tang (Zebrasoma xanthurum) is one of the most recognizable and sought-after tangs in the marine aquarium hobby. Traditionally, keeping one meant relying on a fish collected from the wild. Today, captive breeding is giving reef keepers another option—and expanding what we once thought was possible in marine ornamental aquaculture.

For this interview, BRStv’s Kyle sits down with Kevin Barden, owner and operator of Surge Marine Life in Sarasota, Florida, to talk about the work behind raising Purple Tangs in captivity.

They cover everything from why tangs are substantially more challenging to raise than familiar captive-bred fish like clownfish, to biosecurity, larval diets, commercial-scale production, and what hobbyists should know when bringing a captive-bred Purple Tang home.

Captive-Bred Purple Tang Interview Topics

Captive-Bred Purple Tang

Captive-Bred Purple Tangs

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Why Captive-Breed Purple Tangs?

How did you get into tang aquaculture and eventually start raising Purple Tangs?

My name is Kevin Barden, owner and operator of Surge Marine Life. I’ve been dealing with tang aquaculture for nearly 20 years now, working originally on the research side of things, and I’ve transitioned over time into the commercial aspect of it.

I started Surge Marine Life about three years ago to do this on my own.

Previously, I was raising Yellow Tangs with Biota. The way it works with raising marine fish is, if you can raise one fish within a genus, then you can translate that technology to raise other fish within the genus.

We were raising Yellows and doing a lot of them, and we had our eyes set on what other Zebrasoma tangs would be a good fit.

Purple Tang has a high demand. It’s a very iconic fish in the aquarium trade, so that was a natural choice for me to want to get those available to the community.

What Other Marine Fish Could Be Captive-Bred?

Could other species in the Zebrasoma genus eventually become available as captive-bred fish?

Sure. I think they should all have captive-bred options. There’s no reason that we shouldn’t be able to transfer that technology to all of them.

There are seven or eight species within Zebrasoma, and there’s no reason why they shouldn’t all eventually make it to a captive-bred option.

What would be your “holy grail” fish to successfully breed and rear in captivity?

That’s a good question. I don’t know that there’s just one. There are so many.

We’ve come a long way with the tangs, getting them commercially done as far as volume and numbers. Angelfish have made a lot of progress over the last 10 years, but I think wrasses are a family that are underrepresented in being raised in captivity. Butterflyfish are another one.

There are some of those big, iconic species—particularly certain species that have problems coming in from the wild, or reasons why they’re not available as often from the wild—where captive breeding can provide an alternative way of getting them into the hobby and getting them more successfully.

There are a lot of stories of fish that just don’t come in well from the wild for whatever reason. If we can make them hardier, more robust, and readily available, those are all reasons to raise them in captivity.

How Surge Marine Life Produces Clean Captive-Bred Fish

How do you make sure your captive-bred fish are as clean as possible?

We really started Surge Marine Life with the intention of wanting to provide the industry with the cleanest captive-bred fish possible.

There’s always been this idyllic idea that captive-bred fish are inherently cleaner. While that’s true, it can really come down to the methods that are used for aquaculturing fish.

If you’re using natural seawater, it depends on how it’s being processed before it’s used. There are also the live feeds that you’re using and whether you’re getting them from a source that could potentially be contaminated.

We wanted to take that idyllic concept of captive-bred fish being as clean as possible and take it to the extreme, so the fish that we send to the end consumer can give them confidence that they’re putting a fish into their tank that’s not going to have problems.

People get scared to add a new fish to their tank because they get stability in their tank and they have no problems with parasites, and one bad egg can ruin the whole thing.

Quarantine is great, but it’s a challenge for a lot of people to do it correctly. It’s a high-risk scenario where you can have problems getting the fish through quarantine before getting it into your tank. During that risk period, you could possibly lose that fish. Then you’re out time, you’re out money, and that fish is now deceased.

We go through an extensive quarantine process with all of our broodstock as they arrive and before they go into our broodstock systems. We’ve also utilized AquaBiomics in the past to ensure, after they’ve gone through quarantine, that they are clean because it’s such an important thing for us.

Having these fish in spawning condition is a very stressful environment to have these fish in. If there is any parasite present in a broodstock tank, it’s going to rear its head. So we make absolutely sure that our fish are as clean as can be.

Even then, when we move eggs from the broodstock system into our hatchery systems, that’s the only time that we’re putting anything non-sterilized from the wild into our hatchery systems.

Our live feeds are all raised here in-house. Our water is all artificial seawater—we use Instant Ocean. All of the inputs that go into the larval system are disease-free, problem-free situations. The only potential contaminant there would be the eggs.

When we get the eggs from the broodstock systems, they’re very robust when they’re eggs. Think about it almost like a chicken egg. You can kind of roll it around. Even the fish eggs, you can roll them around in your fingers and they don’t just pop. They’re very hardy at that stage right before they hatch.

We can disinfect the eggs. We use hydrogen peroxide, clean the whole outside of the eggs, and rinse them really well. We’re making sure we’re not transferring anything with the eggs that we’re not intending to.

That way, when we get the fish raised, they’re staying in a system that has never been exposed to any other wild fish.

By drop-shipping and sending the fish directly to the consumer, we’re getting the fish straight from our clean hatchery right into your tank, and they’re ready to go without quarantine.

We consider it a quarantine-clean fish that’s done without the need for any of the harsh chemicals that are usually used in quarantine.

Why Captive-Bred Purple Tangs Can Work at Commercial Scale

What makes Purple Tangs commercially viable to raise through aquaculture?

It’s something that should hopefully, over the long term, only improve.

Tangs have a high fecundity, which goes into that pelagic spawning method where they’re releasing a lot of eggs into the water column. That gives us a lot of eggs to work with even with very few numbers of broodstock.

As we work to improve our methods, we can increase the yield, raise more of them, and hopefully only drive that price down.

The other thing about wild fish is that there are availability issues throughout the seasons. Especially if you’re looking for small ones, they can kind of peak and disappear at certain times of the year.

With aquaculture, we can have them available year-round with a reliable source and a clean source.

Why Are Tangs More Difficult to Raise Than Clownfish?

What makes raising a Purple Tang different from raising a clownfish or dottyback?

What it really comes down to is what we call the pelagic larval duration. It’s the time that the fish goes from an egg to a juvenile fish.

The longer that stage is, the longer they’re in this really delicate phase of their life.

Typically, pelagic-spawning fish—the parents release the eggs into the water column. They come together, usually in the evening right before the sun sets, and they release gametes into the water column.

There’s no parental care from that point on. There’s no energy expended from the adult fish’s perspective.

Their strategy is to release a lot of eggs into the water column, and they’re on their own from day one.

They typically hatch out quicker and a little bit underdeveloped. They hatch into what we call a prolarva, and over the first couple of days they’re still developing the functional parts that they need to even hunt in the open ocean.

Their digestive system is not completely established yet. Their mouth is not fully open yet. Their eyes are still not fully developed, so they can’t even see.

It’s usually anywhere from two to four days before all of those things come together and they start feeding. Over that time, they’re using the yolk sac that they got from the egg and the mother parent.

Once they transition onto feeding exogenously, or hunting out in the wild, they’re on their own. It’s just a long, very delicate process that they’re trying to survive through.

The survival estimates in the wild are somewhere around 0.1%, so that’s about one in 1,000 eggs making it to a juvenile fish on the reef. That’s why they’re putting as many eggs out into the water as they can, hoping that they can get a few offspring to survive and continue on the genetics.

How does demersal spawning differ from pelagic spawning?

Conversely, demersal-spawning fish usually produce bigger eggs and much smaller spawns, and they put the eggs onto some kind of substrate.

That could be underneath a coral, or in an aquaculture setting it might be on a tile or PVC pipe.

There’s typically parental care involved as well. One of the adults will stay with the eggs while they’re developing. They usually develop for a much longer time. With clownfish, it’s about a week.

The parent will fan the eggs and go through them and pick out any that might be molding and could contaminate the rest of the batch.

There’s a lot of parental care that goes into it, and they have a much higher percentage that are going to survive because of that.

When you think about demersal versus pelagic spawning, they kind of equal out. The demersal spawners produce fewer eggs, but more of them survive. The pelagic spawners are producing a whole lot of eggs and much fewer survive, but recruitment on the reef overall kind of stabilizes between the two reproductive methods.

For aquaculture, though, pelagic-spawning fish are much more difficult to rear. It’s just a much more delicate fish larva to work with.

With the demersal spawners, the aquarist can do a lot of that husbandry that the parent fish would be doing and help them along. Those fish have a much shorter pelagic larval duration, so they transition onto bigger foods quicker.

They’re generally a more hardy fish to work with.

The Biggest Challenge Isn't Getting Tangs to Spawn

What are the biggest challenges when raising pelagic-spawning fish like tangs, wrasses, and angelfish?

For the most part, getting them spawning is typically not the hard part.

You’d actually be surprised. A lot of hobbyists probably have fish spawning in their home aquariums and they don’t even know it.

These fish want to reproduce. They’re genetically engineered to do it. Like I said, there’s very little energy expenditure from the parental perspective to just be releasing eggs out into the water column.

They pretty readily want to spawn as long as the conditions are right.

We strive to keep our aquariums with stable temperatures and a long photoperiod—that daylight time. Those are the kinds of things they’re looking for as triggers to spawn.

Getting them spawning is usually not the challenge. It’s almost always the larval period.

We’re always looking for fish to work with that ideally have a shorter larval period, which means it should be a little bit easier to raise.

There are always different stages along the development that can be more challenging with certain species that we’re still working to crack the code on.

But it’s a fun field to work in and try to crack those codes.

What Do Captive-Bred Purple Tangs Eat?

What do Purple Tangs eat from the larval stage through the juvenile stage?

When they very first start eating, they’re eating Parvocalanus copepods. It’s a small species of copepod, and we actually feed the nauplii—the baby copepods.

It’s a very costly, expensive, and challenging process raising those copepods. That’s a big part of what separates out these pelagic-spawning fish.

Being a smaller larva means they need a smaller prey item. The copepods that we use have just the proper nutrition right from the get-go to get them off on the right foot.

Once they’ve had a period of time eating those, we transition onto bigger foods. We go to rotifers and use Artemia nauplii as well.

Throughout that whole process, we’re also transitioning them slowly onto inert diets, like mini pellets. Basically, it’s a micro diet—a crumble of a pellet like what you’d be used to using.

As the fish grow, that crumble size increases, and eventually they’re just on a traditional pelleted diet, just like you’d feed at your house.

Why is algae such an important part of a Purple Tang's diet?

Once they go through metamorphosis, they’ve made that transition from the pelagic phase up in the water column down onto the reef.

When that physiological change happens is when they kind of change their diet as well. That’s when we start offering them some things to graze on.

I consider them an obligate herbivore beyond just calling them an herbivore because, physiologically, they have a very long digestive tract that’s designed to be processing marine algae products.

If you’re not giving them those kinds of things, they’ll obviously love any kind of meaty foods that you give them, but it’s kind of like giving your kids candy. It’s not necessarily what they need.

I really try to push people to make sure that they have some kind of algae available for the fish pretty much at all times.

That’s their natural behavior—to just be constantly grazing, not eating small meals just a couple of times a day.

Why should algae be a major part of a tang's diet?

It also means these captive-bred Purple Tangs are already accustomed to foods commonly available to hobbyists. You’re not bringing home a wild fish and discovering that it will only eat one particular food, then doing all the work of transitioning it onto a healthier captive diet.

With aquacultured fish, you can hit the ground running. Their diet is already sorted out and they’re ready to go.

How to Acclimate a Captive-Bred Purple Tang

What's your advice for acclimating a captive-bred Purple Tang when it arrives?

It really depends on the tank that you have and the tankmates that fish is going to be joining, but almost always I like to recommend an acclimation box when you’re adding these fish.

It gives them an opportunity to get exposed to the fish that are in the tank, and also gives the fish that are in the tank an opportunity to get exposed to this fish.

What you don’t want is to just drop this fish right into a tank that has some other tangs or bigger, aggressive fish that might see them as a threat entering their territory.

When you take the fish out of a box that’s been shipped overnight, it’s been in darkness for the last 24 hours. If you just drop it right into a tank where those other fish are comfortable and settled in, you’re dropping it into an environment that it’s not prepared to defend itself in.

The acclimation box is great. It gives you an opportunity to observe the fish and how it’s interacting with its tankmates before releasing them all together.

Other than that, turn off the lights before you add the fish. Like I said, they’re coming out of darkness.

The whole goal with adding the fish into the tank and that whole process is just trying to keep the stress down.

Everybody wants to have the fish in their tank, turn on the lights right away, and see what they got. But having patience, trying to keep stress down, and not trying to speed up the process is really important.