About harpacticoid copepods

[Luis A M]

Reading my previous posts,people could think that I am a fan of calanoid copepods and that I hate "harps" Not at all,I like harps,and enjoyed collecting them from my tanks and watching their fascinating life cycle.I designed a method for mass producing them that I will share later.
As most aquarists (and herpers)I raised many kinds of "live food"for my pets,and many times I had more fun breeding the prey animals than the predators!
Now that it is clear that I don´t hate harps and that I like raising them,I must be honest and say that I don´t think they are useful as larval or fish food.
This is my personal opinion and I welcome any different thoughts to be debated here.Let´s get deeper into this.
Harps are present in virtually any aquarium,especially those with rocks,gravel and plants.They can be seen crawling on all substrates and ocasionally swimming fast across the water.Here they help as micro scavengers,eating small left-over particles that otherwise would increase the burden of our skimmer and WQ treatment system.
But they are not taken as food by fish,other than by mandarins.Let me know if somebody observed any other fish definitely feeding on them.
They are hatched as nauplii that are also substrate dwellers.These look like microscopic roaches,very different to calanoid/cyclopoid nauplii in appearance and behaviour.Therefore they are not larval food.
Summarizing,harps and their naups are benthic,crawl on substrates,feed on detritus,and hide from the light.Few fish and no larva feeds on them.
Calanoids and their naups are pelagic,filter feeding on algae,swimming in open water.They are the preferred and natural food of fish and larvae,and are atracted to light.

That being said,and as nothing is absolute in biology,there are exceptions.
Among the thousands of harps species,there is one very atypical and interesting for aquaculturists:Euterpina acutifrons.
This harp is planktonic and filter feeder of algae,like calanoids.Same are their naups,which are very small.This species is raised like calanoids and said to be much more harder and productive.Though this harp is found in many areas of the world,it was only in Hawai that it was cultured and used in aquaculture(Syd K.,Waikiki Aquarium).

Some harps are said to be "partly pelagic"or that they being benthic,their nauplii are pelagic,and good larval food.Most of the times this didn´t stand true.Again with one exception;there is a scientific work that shows that the benthic Tisbe holothuriae has planktonic,atracted to light naups that could be collected and given to larvae.It would be interesting to find if these naups were accepted by our fastidious ornamental fish larvae...

Again,please submit any personal experience or serious work showing how other harps could be useful.It would be great,given that as a group,they are so prolific,hardy and easy to culture.

[Luis A M]

Harps are very hardy,easy to culture and prolific.I raised many species collected from my tanks or from the sea.I also cultured once a species offered commercialy,Nitokra lacustris.

KEEPING STOCK CULTURES
A good way to collect harps in an aquarium is to put several pieces of PVC piping in there.Harps congregate in them looking for dark places.The pipes are lifted after some time covering both ends and their content emptied in Petri dishes.
Stock cultures were also kept in Petri dishes.I kept them separated by species.If more than one were collected,I pipetted some egg carrying females of each species to start pure cultures.Food was a small amount of "Mikromin",or any grounded flake food.Changing water was done by simply empting the dishes and filling them with new water.Many harps remained in the dishes to keep the culture going.
The culture dishes could be directly observed under the microscope and the life cycle of the copepods checked.I was particularly trying to find some species that produced pelagic nauplii,which could be used as larval food.I never found any.

MASS PRODUCTION
I designed a good and simple method for mass producing harp copepods.The idea was to feed mandarin fishes kept in small breeding tanks with them,instead of having to depend on the natural production of a large full of rocks tank.The system was very successful.But then I found tha mandarins could be weaned from their copepod natural diet to artemia, later to frozen mysis and finally compound pellets.So culturing harps lost their meaning.
Cultures were kept in trays.Any tray will do,but I used old photography processing trays,as they have a convenient spout for emptying them.
The original idea was to let them under sun light until they were covered with algae.But that proved to be unnecessary;harps propagated well in clean trays.Food was Mikromin.I kept some few trays.When one was ready to harvest,I poured the water thru a 53 mic.sieve and refilled the tray with new water,as with the dishes.No aereation was provided.

[chris melb]

Thanks for providing this Luis, ive been reading a bit about Harps, your fod source "Mikromin" what is that exactly? (i tried to google it - came up as hair loss treatment), are there any other suitable feeds? phyto? they are known as detrivore consumers am i right? youve mentioned ground flake is that still ok for mass culture? ive also read from seahorse forum that flax seed oil can also be used basically for enrichment. Although it sounds that Harps may not be all that beneficial for larvae i still think play an important role as a clean up crew in systems.

[Luis A M]

Mikromin is a fry food from Tetra,powdered Tetramin.Any grounded flake food is fine.Microalgae only becomes food when it sinks to the bottom and form part of detritus.Fish flake food is taken right away and is nutritionally convenient.

[aomont]

Luis,
The trays were inoculated only once and then kept until harvest ? You harvested everything and started new again ? No water changes/top off ?
How long from seed to harvest ?
Thanks,
Anderson.

[Luis A M]

I gently poured all the water into a 53 mic sieve.Then refilled.Enough harps remained attached to the tray to keep the culture going.Two days or more between harvests.

[chris melb]

Hi Luis are your setup seems so simple yet im still having problems getting my harps to increase in population, i have them in small A4 paper size clear trays, holds about 6 litres in total,

i have three trays in total with no areation and are kept in the dark

Tray 1:crushed pellet food by sera
Tray 2: live T-iso
Tray 3: live TET

From what i have read and you have posted they are detrivores, so the live algae may not be best i understand but wont it form as detritius and then become a good food source? I mean dont people notice a bloom in pods when they dose there tanks with DTs

The crushed pellets are mashed and crumble to a very fine powder in my hand is this small enough? or does it have to be like a liquid form? Would V8 veggie juice be more suitable or does it have to be a crushed flake food I have CE flake, maybe i could try that.

all my cultures are still alive but im not seeing the numbers increase nor am i seeing any mini harps (i use a magnifying glass to look for them) im assuming looking for mini harps is a good indication of how the population is doing.

[Luis A M]

Harps are detritivorous.Crushed flake food is about perfect.Any other thing would work but why bother?.Phyto,V8,will eventually become detritus but leaking lots of unwanted pollutants in solution

[aantreklik_jared]

My observations about Harp pods is that I successfully replaced BBS from days 4-9 in clown raising. An interesting observation... by no means proven was that this batch had a much deeper red/orange colour to my normal batch. I must say I did this out of necessity... not planning... however I plan to study this when I next raise a hatch. I believe that the larvae may have preference to BBS... although I will be testing this in the next hatch. FWIW, The larvae successfully completed meta on days 8 and 9, while feeding on Harp pods

[KMB]

Do you know which species of harpacticoid you are using? I also sometimes use harps (Euterpina acutifrons) after day 3 if I forget to hatch out Artemia. I can't say that I have noticed any color difference in the clowns but I haven't looked for it. I will be more aware of that and will try harps on purpose for the next batch just to see.

What are you using to feed the harpacticoids?

Karen

[aantreklik_jared]

I am feeding them on Rotimac... I haven't identified them to species yet... but it is on my to do list..

[mrblue]

I have also had some interesting observations with harps. Without a microscope I couldn't be 100% but after Aantreklik_jared told me about his success feeding his larvae on them I'm certain I am noticing similar things.

In my rotifer cultures harps appear to be breeding almost as rapidly as the rots. Interestingly they will accumulate at the surface with the rots so I collect a lot of them whenever I collect rots. For some reason if you leave them sitting in a jar the majority will 'stick' to the side of the jar. In the same way once they get in the larvae tank the majority appear to stick all over the glass. In some cases there are so many on the glass I can barely see in to do water changes.

Most species ignore them initially but generally at some point (different for different species, usually at least BBS period) they will notice them and then start hunting them off the glass. Some species (or just some batches) will really get into them and will massacre the entire population, leaving nice clean glass. I've never been sure if they made any great difference but after hearing that Aantreklik_jared replaced BBS with them I am starting to suspect they might have.

With some batches of ocellaris I have quite abnormal results and I have suspected these little bugs as the cause. I have had batches of ocellaris with 90%+ survival rates with meta around day 7 with only starting on minimal BBS at day 6 and using no otohime. Other batches have not been so successful for no apparent reason, it seems it happens more often with my black ocellaris batches but this might just be coincidence. I can't help thinking that maybe it is something as simple as the position of the overhead light, or their larval light, or a combination of both that dictates whether one batch will see and hunt them and another one wont.

I'm probably just seeing things but I thought it was worth mentioning. Something is definitely going on. A microscope will be at my disposal any day now so I will be able to confirm this soon.

[mrblue]

I just had a look at my 'harps' under a microscope. I took 5 random samples out of the water column of a rot culture of mine and one off the side wall of this culture and there were pods in them all. It seemed no matter where I got the sample from there seemed to be similar numbers in each of them, from a rough estimate I would say about 10% of the total population. The weird thing was that there was lots of shed shells/skins in the sample, it seemed maybe more then the amount of pods I saw. At first I thought I was looking at a few different species but I am now fairly certain it is just one species, just at many different stages, from tiny naups smaller then rots up to huge possibly egg carrying adults around BBS size.

The weird thing was that there was no where near the numbers of critters I have seen stuck to sides of tanks and the side of collection jars, as I describe above. I collected a whole bunch of these things stuck to the side of a collection jar and they all appeared to be smaller eggless rots. In fact it seemed like they were attaching themselves to the bottom of the petri dish as I was viewing them. What's going on here, any one heard of this? They seem to be able to attach themselves quite strongly to a surface, if I siphon the water out of jar they are stuck to, they remain stuck to the glass even out of water.

With the actual pods I think I will have to try to separate them from the rots and see if I can raise a batch of clowns or something off them exclusively. Does anyone have an idea how to do this, I guess I could probably screen off the rots leaving a few adults to start a population. How would I id them as either a harp or calanoid, they seem to spend a lot of time swimming for a benthic pod? Whatever they are they appear quite virile, I turn over my rot cultures really quickly and basically harvested them almost to nothing with that recent dotty back attempt. The culture I collected them from was totally restarted a little over a week ago. I had gone through half the culture over the last week and topped up 50% the day before I took the samples so this wasn’t just a build up of pods in the crud at the bottom of a culture.

Are then any id sites for pods? I also had a look at my calanoids and they appear to match the earlier description I gave, although it appear there is also a larger species mixed in with this smaller one. Naups are so small and quick I don't know if that is what I am looking at so I wanted to have a look into iding them before I said anything much.

Ryan.

[Luis A M]

Ryan,you most certainly have harps.Please read up in this thread and the companion calanoid threads for my thoughts on their value as larval food,collecting,culturing and ID them.

[mrblue]

I have read your threads Luis, this is why I am commenting. As I said above I believe my larvae might be eating my harps, I often see them pecking at the sides or the bottom of their tanks. I am certainly adding a reasonable number every time I feed rots and the fact is some larvae clean the tank of them. I keep very clean rot cultures so I also suspect this pod might also be a filter feeder, can a decent population be maintained off very limited detritus? From the samples I collected I might also suspect these harps are not as constrained to a benthic environment as they should be. Just thought it would be something interesting to fiddle with. I thought I could try and seperate them and then start a decent culture, then see how larvae react to them, check stomach contents etc. You said there may be exceptions to the general rule that harps at not suitable as a larval feed, maybe I have one.

So what's going on with my rots sticking to things? I know it sounds crazy, I just assumed they were pods, unless I am seeing things.

Ryan.

[Luis A M]

Great Ryan,keep searching new paths! You might have noticed that my opinion is strongly leaned to calanoids vs harps in the larval raising match
I want to save people discouraging experiences,but I guess I overdo it
Yes,rots do attach to substrate with their tails.Brachionus much less frequently than other genera.

[mrblue]

Great Ryan,keep searching new paths! You might have noticed that my opinion is strongly leaned to calanoids vs harps in the larval raising match
I want to save people discouraging experiences,but I guess I overdo it
Yes,rots do attach to substrate with their tails.Brachionus much less frequently than other genera.

I will keep searching, even if it is in vane LOL. I'm sure your opinion is right in favouring the calanoids, I don't think the harps wil ever be quite as usefull but it doesn't mean they might not have a use.

So why have I never heard that rots can attach themselves to substrates , sounds like that would be important. I wonder if it has affect on feeding larvae, I do often see the glass of a larvae tank covered with them.

Ryan.

[KMB]

Mrblue, I've never heard much about rotifers attaching to the substrate either but it happens all the time in my tanks. They get quite dense on the glass and the clown fish larvae are all face up against the glass eating them, then on other runs the clowns don't feed that way at all. I've noticed that when I have less phyto in the tank there seem to be more rots on the glass but that's just a casual observation.

Karen

[mrblue]

Karen,

I'm glad I'm not the only one seeing this. It's weird how some times they eat them off the glass and others times they don't. As I said above when i thought they were pods, I'm sure it is something simple like the position of their light, or the position of the overhead light that will result in them striking off the glass. Makes me think that if you could work out what factor encourages them to eat of the glass you could more realistically attempt to raise larvae off harps.

It also makes me concerned there could be adverse affects to the rots doing this, like over stocking the tanks with rots, oxygen depletion etc and I guess there could be issues with them bumping, or striking against the glass.

Ryan.

[KathyL]

I have also noticed rots attaching to the glass of the tanks and to the petrie dish under the microscope. They seem to have a sticky tail.

[mrblue]

Interesting. What do people think, should this be a cause for concern, or could it be a good thing in relation to feeding harps?

[chris melb]

IME i have seen rots cling to the glass/surface when they become shocked or under stress i.e a sudden drop in temp, salinity, etc.

[mrblue]

I'll have to keep this in mind. My ones will cling to the glass if I scoop them out of there cultures and just leave them sitting in their own water for a few minutes. I guess I am stressing them with limited oxygen in this case, what doesn't stick to the glass accumulates at the surface. I wonder if this is the factor they sees them sticking to the glass in my larval tanks. I wonder if I should just invest in a oxygen meter, does anyone use them?

Ryan.

[clayton smith]

Interesting thoughts Louis although I must say my own experience with harps (T. californicus and another unidentified harp) have been somewhat different. I have seen many species of adult fish feed on these copepods, from Dottybacks, Grammas, Bangaii, Damsels, all feeding on them with relish.
I have also found them very beneficial in larval fish rearing with P. fridmani showing much better growth and survival rates when fed on rotifers and T. californicus rather than rotifers and artemia. Larval fridmani would start to take the smaller pods from around day 6-7 from what I could see, possibly even earlier but I did not examine any gut contents so could not be sure that it was earlier than this stage. They have also been very successfull when used exclusively in rearing bangaii.
When unable to collect wild plankton I would always choose T. californicus for larval fish raising over artemia as they are far superior. However I am sure there may be better alternatives that could be cultured.
Here in the UK I am not aware of any other species of copepod being used for fish rearing in the ornamental industry, we are pretty limited to artemia, T. californicus, a couple of people might be using Tisbe and rotifers.
Are there any other species of small copepod that you are culturing?

[Luis A M]

I am keeping A.tonsa and P.pelagicus now.I lost my P.scotti from which I failed to store viable eggs.
Never kept T. californicus but all the harps that sometimes cover the glass and other substrates,are ignored by my fish,only mandarins pick on them.Perhaps I just didn´t met the right fish with the right pod!