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Filter for rearing fry

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  • Offline wbarsuhn
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Filter for rearing fry

« posted: 2 years ago »
I have tried the following while attempting to raise Erectus fry:
1. Fish bowls with enough aeration to keep the fry gently rotating - it works for awhile but takes lots of work to keep clean
2. Small tank with enough aeration to keep the fry off of the surface - still takes lots of work to keep it clean enough
3. Small tank with a sponge filter - this was the most successful in keeping the ammonia level down

I have not had success in getting the fry past about 8 weeks with any of these methods and I think it is because of the constant battle with the ammonia level.  So I am looking into different filtration options for raising the fry and based on my available space a system that utilizes a sump is out of the question.

What are other people using for filtration in their fry tanks, and has anybody used an algae scrubber with fry?  I'm considering building a scrubber that will sit above the tank and drain back into the tank.  If I seed copepods into the scrubber the copepods will be able to feed on the algae and also get washed back into the tank for additional food for the fry.
  • Offline TamiW
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Re: Filter for rearing fry

« Reply #1 posted: 2 years ago »
I do the fishbowl method right now, and use phytoplankton to both help keep the food enriched and keep ammonia down. You're right, it is a lot of work.

I've also used BRT (blue or black round tub) with a sump underneath and cycled media. I wasn't happy with this setup for a few reasons, but the centralized filtration helped a lot. I will be going back to something like this when I eventually build out a larval rearing station. The BRT's I was using were 5 gallons, which I think were too small. It worked okay for erectus fry, but not great for H. reidi - I want to try something larger, but also kreisels on a shared sump.

What's happening when you're losing them at 8 weeks? Is it possible it's food, not water quality? 8 weeks is around the time they really start needing a bigger food.

I would assume an algae scrubber would be fine. The only concern I might have is if you have some particularly aggressive amphipods, they may go after very young fry. Some species seem to, and you're almost guaranteed to get amphipods with an algae scrubber.

Keeping the aquarium clean for any fish rearing is a lot of work, and seahorses it's doubly so because of their propensity to get bacterial infections. If you can raise them in larger volumes of water, that can help enormously, but there still is a lot of daily cleaning. IIRC @DanU uses 90 gallon BRTs, and still cleans the bottoms and sides daily.

Also, have you seen this?
  • H. erectus, H. comes, H. kuda, H. zosterae, Doryrhamphus excisus, Bryx dunckeri, Corythoichthys flavofasciatus
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  • Offline Bruce
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Re: Filter for rearing fry

« Reply #2 posted: 2 years ago »
Tami answered most of your questions but I would like to add a couple of things.

First there is no easy way to raise seahorse fry. It is very hands on and requires a lot of observation time. When you are feeding you need to watch to be sure all is well with the fry and that they are actively eating. You also need to provide the right food for the various stages of fry growth.

I used all three of the methods that you mentioned and I liked the fish bowl the best, at least for newborn fry. I did up to five feeding and water changes a day for each bowl and completely sterilized everything every five days. That means you have to have extra bowls ready to go.

I only used natural seawater taken from Scripps in La Jolla that had been run through 5 large sand filters and stored in a holding tank for use in the Birch Aquarium. Since the water was always the same all I had to do was make sure the temp matched and I was free to do 100% water changes. The water was free but I had to drive 5 hours round trip to get it every week. I realize that most people do not have a reliable source for natural seawater but you can also mix larger amounts to maintain consistency.

I agree with Tami about the algae scrubber, you could be adding non desirable things to your fry tanks including hydroids. As far as ammonia is concerned I am sure that DanU has the best methods and I would look at the link in Tami's post. I used massive water changes to keep the water in tip top shape.

Raising seahorse fry is never easy but there are few things in the world of hobbies that are more rewarding in my humble opinion. Once you have a tank full of juvies that are thriving it makes all the work seem worthwhile.
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  • Offline wbarsuhn
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Re: Filter for rearing fry

« Reply #3 posted: 2 years ago »
Thank you for the input.

Currently my schedule allows me to feed 3 or 4 times a day, but unless I can figure out a way of doing water changes more efficiently I only have time to do this once or twice a week.  My reason for thinking it is an ammonia problem is based on the level that it sometimes get to before I can change/clean the tank.

I don't think it is a problem with the food since I am using Dan's feed after the first week but it is probably less of a cause than the ammonia.  I might also consider using two sponge filters that have been aged to try to slow down the ammonia levels.

I like the idea of adding phyto to increase the nutritional value of the BBS, but how does that help in keeping the ammonia level down?
  • Offline rayjay
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Re: Filter for rearing fry

« Reply #4 posted: 2 years ago »
The live phyto consumes ammonia as a food and then the nauplii feed on the phyto.
I also like to add ClorAm-X to the fry containers as an insurance.
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