How to: Clean, easy and highly nutritious greenwater culture for Daphnia and Moina.

[louis_last]

That's interesting as I've not actually changed the water in their tank - ever.

what's your setup like? are there plants and snails in there and what size of tank are you using? I found a video on youtube recently where someone was reporting that contrary to conventional wisdom they found that daphnia cultures without snails were slightly more productive.

 

[Myrtle]

what's your setup like? are there plants and snails in there and what size of tank are you using? I found a video on youtube recently where someone was reporting that contrary to conventional wisdom they found that daphnia cultures without snails were slightly more productive.

It's very basic, no snails, a few floating salvinia plants that quickly die when I bung them in but there is a fair bit of algae on the glass and mulm/algae on the bottom as well as a couple of leaves. It's on my windowsill but I've only just got round to plugging in the cheap, rubbish light on the tank lid.
It's only a 30l tank, a Ciano one from pets at home. Maybe being tall with a tiny footprint makes a difference?! It's definitely not a tank you'd keep any fish in!

 

[brhau]

I'm still experimenting and fine tuning. There's obviously got to be an optimum ratio of carrot to water that would produce the best results. There may be better vegetables to use too. It was someone in Asia who tipped me off to this and said that they start all their cultures this way, only transitioning to yeast feeding once they are in much larger culture vessels. They said 1cm cubed of carrot or potato per liter of water, I went with carrot because it contains more sugar but sweet potato might be interesting to experiment with too.

Are you always reseeding from the "fast" carrot culture, or do you also maintain a slower growing culture (for when you go on vacation, for example). If so, what do you feed that?

Alternatively, could you just harvest the carrot culture, replace the carrot with some old leaf litter, and then allow the remainder to go into diapause? Then wake with a water change upon returning from holiday.

Cheers

 

[louis_last]

Are you always reseeding from the "fast" carrot culture, or do you also maintain a slower growing culture (for when you go on vacation, for example). If so, what do you feed that?

Alternatively, could you just harvest the carrot culture, replace the carrot with some old leaf litter, and then allow the remainder to go into diapause? Then wake with a water change upon returning from holiday.

Cheers

Exactly as you say - If I'm not going to be culturing moina for a while I just let them produce ephippia by feeding way less. It's very easy to visually differentiate between an adult moina that's carrying embryos and one that's carrying ephippia and you can also see the shed ephippia on the bottom of the culture very easily with a torch so you can tell if it has worked. Fresh ephippia sink so you can then just pour off nearly all of the water and leave the empty culture vessel in a cool dark cupboard and forget about it. The small amount of remaining water will evaporate and dry out the ephippia and whatever detritus is on the bottom with them. That detritus will provide an important source of bacteria for the newly hatched moina to first feed on when you eventually rehydrate them.
The carrot method is also useful for this because it's a food source that eventually naturally winds down gradually and causes them to produce ephippia so if that was your goal you can just start a small carrot culture and forget about it on a shelf somewhere.
After the ephippia have fully dried out I find that they float when you add water again and especially in smaller containers the surface tension draws them to the edges where they stick and are left behind if evaporation causes the water level to fall even a little. Just allow this to happen and then top up with a little more water and they will remain stuck to the sides of the container but this time submerged. Bright white light seems to be more important to triggering hatching than any particular temperature range but warmth should accelerate the process. It can take up to two weeks for them to hatch though but it can also happen within 48 hours and I really don't have a good grasp on exactly what influences this.
I've only ever kept the ephippia in a cool dark cupboard and they have always hatched fine for me after months of dessication but I understand they last longer and you may get better hatching rates by keeping them in the fridge.

 

[louis_last]

By the way if anyone is interested, after a lot of searching I've found a source of high quality ceriodaphnia dubia ephippia. A company called microbiotests in Belgium can supply them to pretty much anywhere in Europe and I can testify that they are comparable to moina in terms of productivity in culture and have real utility as a livefood for fry being that the adults max out at around 1mm.
I'll let you find out for yourselves how much they cost - just make sure you're sitting down and have a defibrillator on hand when you receive your quote.
I think it surely must be possible to source them from some water toxicity testing company or a university aquaculture department in the UK.

 

[brhau]

I've also found that overcooked carrot is a viable food for moina and perhaps the least effort intensive method of production. You can simply boil a slice of carrot for half an hour or so and then add it to water, keep it warm and once the water appears slightly cloudy (after approx 48 hours depending on temperature) add a few moina. There's no need for any supplemental feeding after this, the carrot feeds bacteria in the water as it continues to break down which in turn feeds the moina. This method may be slightly less productive than others but has the advantage of requiring very little input after setup. For feeding a 10 gal tank you can rotate between two 32oz plastic cups innoculating a new culture with a few moina each week or so and being able to feed a decent amount of moina from the active culture twice in roughly the same period. I also notice that moina produced in this way have a noticeable orange colour so it may be the case that there's caratenoid pigments which could be passed onto your fish.

I'm trying this, and it seems that the "keep it warm" part is necessary. Unheated at 18C, the moina survive but are very slow growing

 

[louis_last]

I'm trying this, and it seems that the "keep it warm" part is necessary. Unheated at 18C, the moina survive but are very slow growing

At 18c you should find that they are slower growing but live longer and become larger. I have a friend that cultures moina and we occasionally swap starters when a culture crashes or there's some other disaster like when I spilled my entire 15L culture all over a carpet floor. He keeps them much cooler and feeds tham algae grown outdoors and their appearance is quite radically different than when I culture the same species at high temperatures.
There's also several different species sold as 'moina' that may represent either moina macrocopa, moina micrura, or various other small daphnids. I'm also culturing something at the moment that is about the same size as moina but is definitely not M. macrocopa or M. micrura. It seems not be as prolific but cultures are maybe a little more stable. Increasingly I feel that when culturing moina one of the keys to success is either culturing them in very large "dirty" cultures or keeping smaller cultures that are as sterile and axenic as possible. Lately with the carrot method I have found there's some kind of fungi that can get into these cultures and grow on not just the carrrot but also the moina themselves and realised I was moving it between cultures by using the same pipette to harvest from them.

 

[Chez_]

May I ask for advice, having read the thread? I'm quite clueless about this and it's a bit trial and error. I acquired some live moina macrocopa three weeks ago (from a bloke on eBay, as you do), and split the 200-ish moina between 2 1-litre kilner jars as instructed, in rainwater from my water butt. I added a pinch of spirulina powder, a pinch of bakers yeast and a tiny airstone to each one, and chucked in a few dried oak leaves. Initially when the water went clear I added a bit more of spirulina and yeast.

Now I have two jars that look like this, filled with busy moina. They are on a south facing window in south-west England (the bedroom, non-tank-obsessed husband is... tolerant) and I stick a bit of card between them and the window glass when the sun comes out.

Every so often I wiggle the airstone around in the bottom and stir everything up -- it's pretty claggy, presumably because of the yeast, having read the thread. I've just chucked in a couple of bladder snails as I was worried there was too much algae build up.

My questions are:

Can I just scoop a tiny net full of moina out and put directly in my community tanks or will I also transfer things that might hurt the fish or disturb my aquarium balance? (I have ember tetras, lamp eyes, neon green rasboras, emperor tetras and honey gourami and lots of snails, shrimp etc)

Can I make another colony or two by simply dividing the colonies I already have?

Should I stop feeding the yeast and only continue with the spirulina?

Do I need to transfer these existing colonies to new jars without the yeasty goop in the bottom?

Thank you in advance. My methodologies for everything I do need to be quite low tech and self-sustaining. I was surprised this worked, tbh, it's attempt number three .

 

[dw1305]

Hi all,

Can I just scoop a tiny net full of moina out and put directly in my community tanks

You can. Ideally you need to thin the Moinia pretty much every day and the easiest way to do this is just to feed the fish.

Can I make another colony or two by simply dividing the colonies I already have?

You should, they are very prone to <"boom and bust">, have a look at <"Feeding daphnia with crushed fish flakes">.

cheers Darrel

 

[Wookii]

Can I just scoop a tiny net full of moina out and put directly in my community tanks or will I also transfer things that might hurt the fish or disturb my aquarium balance? (I have ember tetras, lamp eyes, neon green rasboras, emperor tetras and honey gourami and lots of snails, shrimp etc)

Yep, no issues there.

Can I make another colony or two by simply dividing the colonies I already have?

Yep - the larger vessel you can put them in the more stable they will be.

Should I stop feeding the yeast and only continue with the spirulina?

I always found yeast fouled the water far too fast. Spirulina was better but the end result still the same. For longevity you really need to see if you can culture some green water.

Do I need to transfer these existing colonies to new jars without the yeasty goop in the bottom?

Certainly large regular water changes are best if you are feeding yeast. Broken down leaf litter in the bottom works wonders too in terms of adding microbial stability and a food source longer term, you could also add some snails to your culture.