Microworms for marine larvae?

[LordJoshaeus]

Hi everyone! I've been doing a lot of research on microworms lately in preparation for getting back into breeding freshwater fishes, and discovered several interesting facts about the wee nematodes; 1, they can be enriched by adding nutrients (such as fish oil emulsions for DHA and EPA enrichment) to their media; 2, while adult microworms are 1500-2000 microns long and 50-70 microns wide, their offspring are born 180-290 microns long and .13 microns wide (!), which could be swallowed by almost any newborn fish; and 3, it is apparently possible to culture microworms on a media moistened with saltwater, which allows the microworms to survive up to 12 hours when added to a marine aquarium (it took some effort, but here's a source I found discussing feeding them to grouper larvae; https://www.bar.gov.ph/index.php/di...89-2003-1st-quarter/3221-jan-mar03-microworms). My question is, could juvenile microworms be used as a supplemental feed for marine larvae? I am currently working on developing a method for separating the juvenile microworms from the adults with a 25 micron filter bag (the idea is that the juveniles will crawl through the filter bag into some collection water). Thanks

(EDIT: Apparently the microworms survive for 12 hours in seawater even if cultured normally...I don't recall how long they survive if cultured in a 'salty' culture to begin with)

 

[ThRoewer]

I would think in general the answer would be "yes". It depends however on a few more factors.

One of the most important would be if the worms would remain in the water column or sink to the bottom.

And larvae react to motion pattern which is why crustacean larvae and larvae of other organisms that have the right movement patterns work best.
Some larvae can be quickly conditioned to snap first and decide if it's edible later. I've done that before with clownfish larvae and this "try everything in reach" behavior is one of the reasons why you can actually raise them entirely on dry food.
Most other larvae are far pickier and inspect their food closely before eating it. The worst I have seen so far are Marine Betta larvae - like the adults they like to study their food for a while and often it has escaped their reach by the time they made up their minds.

I know that with groupers and snappers, larvae cannibalism can actually be a problem at later stages - they just eat everything that comes in front of their snouts and they can eat large chunks.

The worms can definitely be a great food at later stages when the larvae eat faster and are less picky.

 

[LordJoshaeus]

I would think in general the answer would be "yes". It depends however on a few more factors.

One of the most important would be if the worms would remain in the water column or sink to the bottom.

And larvae react to motion pattern which is why crustacean larvae and larvae of other organisms that have the right movement patterns work best.
Some larvae can be quickly conditioned to snap first and decide if it's edible later. I've done that before with clownfish larvae and this "try everything in reach" behavior is one of the reasons why you can actually raise them entirely on dry food.
Most other larvae are far pickier and inspect their food closely before eating it. The worst I have seen so far are Marine Betta larvae - like the adults they like to study their food for a while and often it has escaped their reach by the time they made up their minds.

I know that with groupers and snappers, larvae cannibalism can actually be a problem at later stages - they just eat everything that comes in front of their snouts and they can eat large chunks.

The worms can definitely be a great food at later stages when the larvae eat faster and are less picky.

Good to hear from someone who has worked with marine larvae my idea was that, when I go to breed marine fish, I would raise the fry on apocyclops nauplii and the juvenile microworms. My thought is that if I fed them both at once, the fry would soon learn that the microworms were food (I've done similar with weaning freshwater fry onto dry food...not 100% sure it works on such young fish, however). When the fry grew big enough, they would be switched to adult apocyclops, adult microworms, and perhaps enriched baby brine shrimp.

 

[ThRoewer]

Good to hear from someone who has worked with marine larvae my idea was that, when I go to breed marine fish, I would raise the fry on apocyclops nauplii and the juvenile microworms. My thought is that if I fed them both at once, the fry would soon learn that the microworms were food (I've done similar with weaning freshwater fry onto dry food...not 100% sure it works on such young fish, however). When the fry grew big enough, they would be switched to adult apocyclops, adult microworms, and perhaps enriched baby brine shrimp.

Have you already figured out how to culture Apocyclops in the required quantities in a rather confined space? That's my problem right now. The way Reed Mariculture suggests it requires a bit too much space...

 

[LordJoshaeus]

Have you already figured out how to culture Apocyclops in the required quantities in a rather confined space? That's my problem right now. The way Reed Mariculture suggests it requires a bit too much space...

I have not. When I get around to trying my hand at breeding marine fish I will need to work on this.

 

[Skydvr]

I was culturing microworms on an instant mashed potato mix quite successfully (not as messy, nasty, or stinky as some of the other methods out there).

My focus is going to be mostly copepods with rotifers to fill in the gaps and then transitioning to TDO. I like the method of producing a wide varied diet, but have space limitations and time constraints makes that difficult. Supplementing with microworms sounds interesting if you can get them to live past 12 hours (though their nutritional value may be lacking by that point). I would be concerned about water fouling if using as a primary feed item with a short lifespan in marine environments. It does require a bottom feeding larvae to be successful as a primary food unless you want to add very small amounts to ensure they get eaten before they hit the bottom.

 

[LordJoshaeus]

I was culturing microworms on an instant mashed potato mix quite successfully (not as messy, nasty, or stinky as some of the other methods out there).

My focus is going to be mostly copepods with rotifers to fill in the gaps and then transitioning to TDO. I like the method of producing a wide varied diet, but have space limitations and time constraints makes that difficult. Supplementing with microworms sounds interesting if you can get them to live past 12 hours (though their nutritional value may be lacking by that point). I would be concerned about water fouling if using as a primary feed item with a short lifespan in marine environments. It does require a bottom feeding larvae to be successful as a primary food unless you want to add very small amounts to ensure they get eaten before they hit the bottom.

I likewise have used instant potatoes in most of my culture endeavors...currently culturing walter worms on them (they are a little smaller than microworms, but more importantly they apparently stay in the water column longer). I will be doing some experiments with getting them to grow on a medium moistened with marine water to see if they will grow on that; when I do breed marine larvae, I am planning on doing a setup like the one mentioned here ( https://www.reef2reef.com/threads/breeding-peppermint-shrimp.579842/ ), which would have circular flow and presumably keep the worms - and any other food items - in the water column longer.