Adult apocyclops in a larval tank?

LordJoshaeus · May 15, 2020

Hi everyone! Here's a question...would there be any benefit to coculturing larval marine fish/ornamental inverts with adult Apocyclops? While most marine larvae are not large enough to ingest an adult Apocyclops (which are 600-700 microns in size) at birth, my idea is that the detritivorous copepods would help process the larvae's waste (I was still going to feed them directly, though) and they would constantly produce 70 micron nauplii that would serve as a supplemental food source for the larvae. I would add some ClorAm-X daily (in addition to water changes) to keep ammonia under control. Thanks

Big G · May 15, 2020

Larry L · May 15, 2020

I think it would depend in the size of the larvae. I saw someone post recently in the "Marine Breeding USA" Facebook group about trying to do the same thing with Tisbe pods, and whatever larvae they were working with were really tiny, and getting eaten by the adult Tisbes.

LordJoshaeus · May 16, 2020

Larry L said:
I think it would depend in the size of the larvae. I saw someone post recently in the "Marine Breeding USA" Facebook group about trying to do the same thing with Tisbe pods, and whatever larvae they were working with were really tiny, and getting eaten by the adult Tisbes.

Wow...yeah, that would not be desirable. Maybe I could put the adult apocyclops in a container outside of the bucket the larvae are in and set up an air powered collector (with a 100 micron screen over the intake) to capture the nauplii produced and deliver them to the larvae being raised?

Larry L · May 16, 2020

It probably will depend a lot on the difference in size between the adult pods and the larvae. Adult Tisbe pods are about 850 microns so a fair amount bigger than Apocyclops. I can't find the Facebook post I mentioned above about adult Tisbes eating larvae, but while looking for that came across other posts where people mention successful co-cultures of larvae with Parvocalanus, which only get up to about 400 microns as adults. So if you have larvae that are not super tiny, it might work really well to co-culture with Apocyclops, probably worth a try.

LordJoshaeus · May 16, 2020

Larry L said:
It probably will depend a lot on the difference in size between the adult pods and the larvae. Adult Tisbe pods are about 850 microns so a fair amount bigger than Apocyclops. I can't find the Facebook post I mentioned above about adult Tisbes eating larvae, but while looking for that came across other posts where people mention successful co-cultures of larvae with Parvocalanus, which only get up to about 400 microns as adults. So if you have larvae that are not super tiny, it might work really well to co-culture with Apocyclops, probably worth a try.

Thanks

Adult apocyclops are 600-700 microns if I recall correctly (though one source stated 400 microns) and are detritivores and algae eaters (they eat a lot of diatoms in the wild apparently), so I am not sure if they would eat fry.

ThRoewer · May 16, 2020

I would say it depends on the size of your larvae. I've added some to my Amphiprion bicinctus larvae and they had no problems eating the adult pods.

LordJoshaeus · May 16, 2020

ThRoewer said:
I would say it depends on the size of your larvae. I've added some to my Amphiprion bicinctus larvae and they had no problems eating the adult pods.

I guess having a breeding colony of apocyclops in with clownfish larvae would be short lived then

ThRoewer · May 16, 2020

LordJoshaeus said:
I guess having a breeding colony of apocyclops in with clownfish larvae would be short lived then

Most definitely!
BTW, how do you culture your Aocyclops and what culture densities do you get?
I would need a ton of them, particularly nauplius larvae, for breeding my Marine Betta and Bluestripe pipefish, but my cultures are kind of anemic and don't get to suitable densities.

LordJoshaeus · May 16, 2020

ThRoewer said:
Most definitely!
BTW, how do you culture your Aocyclops and what culture densities do you get?
I would need a ton of them, particularly nauplius larvae, for breeding my Marine Betta and Bluestripe pipefish, but my cultures are kind of anemic and don't get to suitable densities.

I am not currently culturing them (chiefly because I am not keeping any marine fish right now) but I came up with an idea based off of Reed mariculture's design. I would have six heated 5 gallon buckets, each filled with 30 ppt saltwater and having a sponge filter with 1/4th of an air line. Each bucket would be stocked with 5 Apocyclops per ml; if I started with nauplii rather than adult copepods, I would wait two weeks for the nauplii to reach maturity before beginning to harvest them. When I do begin to harvest them, I would use a 1/4 inch ID piece of silicone tubing (with a 100 micron filter bag tied to the end in the bucket) as a gravel vacuum to remove most of the water (and the nauplii in that water) without sucking up the adult copepods. The nauplii would be harvested with a 25 micron filter bag and fed to fry/used to start another culture, and the water would then be returned to the bucket. After six weeks, the bucket would be restarted with new saltwater and harvested nauplii. Rotating the buckets like this would mean I always have at least two (and usually four) buckets I can use to feed larval fishes; Reed mariculture stated that this design would give 80,000-100,000 nauplii daily per 15 gallons of culture set up like this (some quick research on mandarin fish fry found that 1+ nauplii per ml of larval rearing water is an ideal quantity for fry growth...for a five gallon rearing bucket, that is about 19,000 nauplii).

The main challenge that I have not devised a solution to yet is how to feed the cultures affordably. Reed mariculture recommends their RGcomplete to feed the cultures, at a rate of 6 ml a day per 15 gallons...getting even a liter of the RG complete would cost me almost $100 after shipping, so this would cost over $35 just to feed the copepods with RGcomplete for a month (several times the upkeep cost of the rest of the setup put together). Need to find a cheaper food source...

ThRoewer · May 17, 2020

My setup is similar to what you plan but I don't use heaters (my garage is warm enough) and I use live algae (green water) as feed.

I started with a little bag of Apocyclops and Nannochloropsis that I added to a 2-gallon acrylic tank with saltwater. The algae that came with the pods as their travel provision multiplied faster than the pods could consume them so the water got pretty dark quickly.
I split the culture twice by now to have 2 2-gallon acrylic tanks and a 5-gallon bucket so I doubt my pod density is at this point anywhere near to what you plan as starting density.
(BTW, where would you get so many nauplii and how much would they cost?)

As for the feed - given how fast the algae multiply under light and the fact that the pods are rather slow to consume them I don't think using RGcomplete is warranted or even makes sense - I may be wrong, time will tell.
Currently, I culture the green water for my rotifers in the backyard with natural sunlight, and that works so far quite well. Once the temperatures go up I may have to change things to prevent the algae culture from being boiled but right now it is extremely effective.

LordJoshaeus · May 17, 2020

Good to see your experiences

I do not know how I will get so many copepods to start (one five gallon bucket would require about 95000 copepods to start...once I have multiple cultures going I could start a new culture simply by harvesting the nauplii from the other cultures). I found an article yesterday on what wild Apocyclops eat; https://pdfs.semanticscholar.org/1632/c84b514a87dfdb531ae73d6f4ef2a52bee4f.pdf

About 50-80% of their stomach content in this study was detritus...wondering if they would do well on certain powdered feeds? The study also found that of the algae that was consumed, 89% of it was diatoms...cyanobacteria of any kind were seldom consumed, and while the Apocyclops did eat some green algae (specifically chorella) it was digested very poorly, apparently because of the cellulose-heavy cell walls that all green algae possess. If the Apocyclops struggle to digest green algae, that could explain how your cultures still have large Nannochloropsis populations (and low Apocyclops populations).

LordJoshaeus · May 17, 2020

Hi everyone! While we are on the topic of culturing Apocyclops (rather than trying to keep adults of these copepods with fish fry), I found this interesting abstract on Parvocalanus; https://www.researchgate.net/public...alanus_crassirostris_Optimizing_adult_density

Sadly, I was not able to find a free version of the whole article...however, the abstract noted that harvesting eggs/nauplii of Parvocalanus multiple times a day led to dramatic improvements in egg/nauplii production, with 40,000 eggs and nauplii (ample for a 5 gallon larval tank like what I mentioned above) being harvested daily from a tiny 1 liter experimental culture with 4 copepods per ml. I wonder if something similar could be done with Apocyclops? (Side note...how much live microalgae would be required to maintain an Apocyclops/Parvocalanus culture? I read on a thread on the Marine Breeding initiative that 8 gallons of Isochrysis cultures were overkill unless you had several hundred gallons of Parvo culture at your disposal).

ThRoewer · May 17, 2020

Great to see that someone else here is using Google Scholar! Got to check those articles out later!
At my previous job, I had access to a lot of those research papers from Elsevier and a few other outlets and downloaded what I could. But there was so much and not enough time. And back then I was more looking for Tigriopus and Tisbe.

These are 2 of my Apocyclops cultures in acrylic containers.

No aeration - just light

And this one I have aerated:

And here a little video showing some adults:

And here a short clip of my improvised outdoors green water culture:

ThRoewer · May 17, 2020

LordJoshaeus said:
Good to see your experiences I do not know how I will get so many copepods to start (one five gallon bucket would require about 95000 copepods to start...once I have multiple cultures going I could start a new culture simply by harvesting the nauplii from the other cultures). I found an article yesterday on what wild Apocyclops eat; https://pdfs.semanticscholar.org/1632/c84b514a87dfdb531ae73d6f4ef2a52bee4f.pdf

About 50-80% of their stomach content in this study was detritus...wondering if they would do well on certain powdered feeds? The study also found that of the algae that was consumed, 89% of it was diatoms...cyanobacteria of any kind were seldom consumed, and while the Apocyclops did eat some green algae (specifically chorella) it was digested very poorly, apparently because of the cellulose-heavy cell walls that all green algae possess. If the Apocyclops struggle to digest green algae, that could explain how your cultures still have large Nannochloropsis populations (and low Apocyclops populations).

I had that article already in my downloads.

A not so ideal feed organism could be one explanation for low numbers. But then, I started only with an 8 oz AlgaeGen pack of Apocyclops and actually harvested some for the bicinctus before setting up more cultures, most of them less than a week ago. I guess it will take a bit for them to reach a decent population density, no matter the feed organism.

I actually have right now a little diatom bloom in the tank with my bicinctus fry. I will see if I can harvest some of that and start a reference culture. If that one does better then I know it is the feed.

LordJoshaeus said:
Hi everyone! While we are on the topic of culturing Apocyclops (rather than trying to keep adults of these copepods with fish fry), I found this interesting abstract on Parvocalanus; https://www.researchgate.net/public...alanus_crassirostris_Optimizing_adult_density

Sadly, I was not able to find a free version of the whole article...however, the abstract noted that harvesting eggs/nauplii of Parvocalanus multiple times a day led to dramatic improvements in egg/nauplii production, with 40,000 eggs and nauplii (ample for a 5 gallon larval tank like what I mentioned above) being harvested daily from a tiny 1 liter experimental culture with 4 copepods per ml. I wonder if something similar could be done with Apocyclops? (Side note...how much live microalgae would be required to maintain an Apocyclops/Parvocalanus culture? I read on a thread on the Marine Breeding initiative that 8 gallons of Isochrysis cultures were overkill unless you had several hundred gallons of Parvo culture at your disposal).