Raising Seahorse Fry: The Fish Bowl Method

By: | Date: 04/03/2003 | 22 Comments |

Seahorse Fry in "greenwater"

The system I use for raising  Hippocampus reidi fry is a modified pseudokreisel. Kreisels and pseudokreisels are tanks with a circular water flow most often used for keeping jellyfish. For H. reidi, and other pelagic seahorse fry prone to air snicking, you can use a drum fish bowl for this purpose.

The design originally suggested by Pete Giwojna was an airline tube, glued half way down the curved side. This makes the water flow in a circular pattern that pushes the fry away from the top and prevents them from gulping air.

illustration of the circular flow of fish bowl kriesels

About the same time I learned about this, I discovered by accident that a batch of fry did better in a “dirty” tank, a tank I didn’t clean out from before the last brood that had failed. I’m now sure it was due to the large number of copepods that had grown from eating the bodies of dead seahorses. Martin Moe even made note that his orchid dottybacks did better in “dirty” tanks in his breeding orchid dottybacks book. If that wasn’t encouragement enough…

So I set out to merge the two systems, and now I use a 4 gallon plastic drum fishbowl with a sponge filter glued to the side. I make my own sponge filters out of open celled furniture foam, which is available at most fabric stores. Opened celled foam means the cells that make up the foam are interconnected and can pass air, water, etc . . . Since it’s not very likely the store will know if it is or not, you’ll have to test it – which means blowing into it and seeing if you can feel your breath on the other side.

Once you have the foam, you’ll need to cut and drill it. I soak it in water and then freeze it, which allows you to saw and drill it more easily. This is especially important for drilling, when the foam very easily binds up the drill.

The shape I make is roughly a square with an angled bottom. (see picture in below link). I usually make it taller rather than longer/wider. Then drill a 1/2 inch hole in the top about half way to three quarters the way down for the uplift tube. From the side that will be facing the inside of the bowl, I drill a whole just wide enough to fit rigid airline tubing – it should meet the uplift tube hole at the very bottom of that hole.

When the foam is drying, I work on the uplift tube. This requires caution because I use a small blow torch to melt the plastic. In other worlds, follow these instructions at your own risk, and make sure to do it in a well ventilated area, as most plastic fumes are hazardous. I cut the length so it goes about a half inch to an inch into the uplift tube hole in the foam, and the rest can be bent so it is just shy of the side of the fishbowl. I heat it up, and bend it with whatever tools I have handing – pliers, fork, pencil… then rinse it under cold water to set it.

Once that is done, cut the rigid tubing so it has an inch sticking out of the foam, and goes back to the beginning of where the rigid airline hole meeds the uplift hole. I glue it in place with silicone glue. I then cover the back side of the sponge filter in glue, and place it along the curved side of the wall near the bottom so that the bent uplift tube meets the fish bowl side about half way up. Then it dries for 24 – 48 hours.

To get the bowl ready for fry, I like to start a month in advance, but two weeks is usually enough time to get by. Unless the aquarium has a known population of hydroids, I start with water from the parents tank. If I have a separate culture, I add copepods and rotifers. If not, the copepods SHOULD be present in the parents tank water, although it helps to siphon the glass of the tank at night.

Once its set up, I add small amounts of food until I see copepods swarming around it, and then start adding more. Frozen mysis and frozen squid seem to work especially well for this, although flake food will work too. If you’re going to add rotifers, now is the time, along with microalgae. Once most of the food is eaten by the copepods, add more food.

When the baby seahorses arrive, change at least half the water with water from the parents’ tank. I transport the babies in the parents’ water after catching them underwater by either using a brine shrimp net and transferring from net to plastic bag underwater, or siphoning them up with an airline hose. This may provide you with enough water. You’ll need to judge the amount of current based on fry behavior. I usually end up turning up the airflow pretty high to keep them off the surface. The appropriate amount of air may seem like a lot, but keep in mind in nature, they’re disperse via the choppy waters of the ocean, so they’re designed to handle it. The fry wishing to “rest” will make their way to the center of the bowl where the current is much less turbulent and hang there.

The seahorse fry will still need to be fed baby brine shrimp, and if they eat the copepods and rotifers too quickly, supplemented with both. But it does get them a great head start on eating. Some won’t take bbs at birth, but will happily take copepods off the sides or when they swim in the water column.

With this system, I do water changes just once a week. It is a real life saver to not have to do water changes every day the first week when they’re so tiny and hard to work around.

I’m still experimenting with what age to move them from this system. At about a month, most have hitched and are preferring to hitch over swimming. However, they still can and do snick air at that age, but not nearly as easily when they are in their pelagic stage. At about six weeks old a power filter (intake well protected) is usual enough to keep them off the surface.

Also about that age, they need to start the switch to larger intermediate foods, the in between foods before they learn to eat frozen. You’ll need to continue to feed bbs and copepods, as they make the switch gradually. The foods can include quarter sized brine shrimp (enriched, of course), juvenile mysis shrimp, baby amphipods, or any other crustaceans that small (peppermint shrimp fry make a great food item at this stage). Without the intermediate food, most will just lose interest in bbs and die. Those that continue to eat bbs may become stunted, especially if they’re not quick to switch to frozen.

Seahorse Fry in modified Fishbowl

Seahorse Fry in modified Fishbowl


Edit 2/14/2013: These days, I still very much use the fish bowl method, but I don’t use the sponge filter anymore. I’ve discovered the fry do much better when you completely clean out the fish bowl every few days. This seems to be similar to Rayjay’s Method of raising seahorses. The key difference seems to be the removal of any build up of bacteria and biofilms. Cleaning and possibly sterilizing equipment every couple days leads to higher success rates. But it is a more tedious method of raising seahorses.

22 Responses to “Raising Seahorse Fry: The Fish Bowl Method”

  1. harry Says:

    that is such a good idea you got there! i never thought that this could be possible. if i get the time i’ll try and make one. this will make it easier for me to take care of seahorses. thanks for the info!

  2. Jay-See Says:

    So this is for breeding seahorse? Nicely done! I love how you do it. I hope I can make one someday. Thumbs up with your creation I like it.

  3. julieta Says:

    looking for a large fishbowl like this. where did you get it? this is awesome

  4. Record Number of Seahorses Born « Seahorse News Says:

    […] bowls they show in the video for raising the little guys. It just goes to show that everybody uses fish bowls for raising seahorse babies! Filed under: Video Leave a comment Comments (0) Trackbacks (0) ( subscribe to comments on […]

  5. Aquagrrl Says:

    The 4 gallon fish bowls are hard to find these days. I had to try companies that sell candy store supplies.

  6. Jimmy Says:

    Does anyone know a specific website that I can order a large fishbowl from?

  7. Jimmy Says:

    I guess I answered my own question here… But here is a a website for anyone who needs it they have up to 16 gallons and they come with a little air system so you don’t have to add as much in


    Just copy and paste…

  8. Jimmy Says:

    Does anyone know if air bubbles will hurt the fry… Also can u use power heads for the fry tank

  9. Aquagrrl Says:

    Air bubbles are fine with seahorses, as long as you don’t have it turned up too high. You also don’t want to use an airstone, just the end of an airline tube. You want the big bubbles as the fine bubbles of an airstone can stick to the fry and cause problems.

    A powerhead on the other hand is a bad idea. They don’t have the strength to swim away from it and will get sucked into the impeller. They’ll even get sucked through the intake sponge eventually.

  10. Jimmy Says:

    Thanks aquagirl but if its not too much can u check my link and tell me what u think about the tank. You don’t have too if u don’t want to… But it would mean a lot 🙂

  11. Aquagrrl Says:

    I’ve seen round bowls like that, used before, and they can work but don’t provide as nice of a circular flow. You’d also want to modify the airline so its at the side, not the center. A drum style fish bowl would be best, but they’re getting harder and harder to find in large sizes. 2.5 gallons are still pretty common and can work if you split large broods between multiple fish bowls.

    There are other things you can do, like put the fish bowl in side a larger aquarium, then cut a hole in the flat side, and cover it with a 250 – 500 micron mesh, and then use a small pump to push water into the fish bowl, and it will come out the side. Another thing I’ve seen is taking a 5 gallon bucket, cutting it down to the width of a 10 gallon aquarium, and gluing the bucket in place. If you’re good with acrylic, or adventurous and willing to fail a few times, you could try making one that will be more structurally sound. However, acrylic can be tough to work with, hence the willing to fail a few times.

  12. Jimmy Says:

    thanks can a jelly fish tank from jellyfish art work with no modifications

  13. Aquagrrl Says:

    I don’t know that anyone has tried it yet. Their tanks are relatively new – I was one of the kickstarter backers for the jelly tank and it’s only been out a few months. That being said, what I’ve seen of it, I think it would probably require the fewest modifications of anything other than a proper larval kriesel purpose made for the aquatic industry, and those cost a lot more.

    I do think you’d have to make some minor changes. You couldn’t use the gravel, the babies would get caught in it. You might have to place mesh over the opening at the base of the bubbles, though I’d first try it without.

    If you do give it a try, please report back how it works for you, I’d love to know!

  14. Jimmy Says:

    thanks aquagrrl! so with the jellyfish tank from jellyfish art all i would have to do is mesh on the bubble output and no gravel… could filter floss work as well?

  15. admin Says:

    On the input side, not the output, because you’re looking to avoid them being sucked into it. I’ve not used filter floss for that purpose, but I don’t see why it wouldn’t work. You’ll likely need to play around with it a bit to see what works best, but you should see within a very short time what is and isn’t working. If the babies are getting stuck to it, it’s not appropriate and you’ll likely need to try something else. Open cell foam blocks might also work.

  16. Jimmy Says:

    Thanks! So the current is already in the tank and I just need to mesh the out put and get the foam blocks for the input

  17. Meriam Cullen Says:

    I thought you are frying those seahorse. Is this a technique where you can breed seahorse without killing them? It looks like an incubator.

  18. Steven Says:

    Hi, my baby seahorses got air in their bodies now. They are floating in the surface of the tank. What should I do? Please advise. Thank you.

  19. Tami Says:

    Hi Steven, it could be for a number of reasons. Most commonly it’s either too much bacterial load in the tank, or they aren’t getting enough food; so they end up floating at the top. If the food is the wrong size and they can’t eat it at birth, that can happen.

    You might want to pop over to the forums and give the details of your setup so we can better diagnose what the problem might be.

  20. timinnl Says:

    Hi Tami,

    Are you still using water from the parent’s tank?

  21. Tamiw Says:

    It depends, really. But usually I am using freshly mixed saltwater (freshly, as in it’s been mixed and sat for a minimum of 12 hours). The only tank water from the parents tank is what I slurp up with the turkey baster.

    I found they are really adaptable at this stage, and starting off with clean water gives them a better start with fewer bacterial problems.

  22. Felicitas Says:

    I’ve been reading some articles on fusedjaw.com.

    Affectionate Raising Seahorse Fry: The Fish Bowl Method | FusedJaw: Seahorses,
    Pipefish & Seadragons | FusedJaw: Seahorses, Pipefish & Seadragons best so far.

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