(20 century author unknown)

Here is the results of my latest little mad scientist experiment. I didn't get really detailed with notes and data as that effort is reserved for more telling projects. I wish I had though, the results were interesting.


I have used a number of different foods for daphnia over the years, from live yeast cultures to powdered algae. Like many other folks, I have gotten mixed results. Some methods produce vast numbers of daphnia and then crash quickly. Others keep a steady flow of daphnia available, but the yields are low.

Thanks to the flooding in my area this summer, I have been able to harvest wild daphnia continuously by (literally) five gallon bucket loads. These are the healthy lively bright orange color synonymous with good caudate food resulting in bright colors. While harvesting, I noticed a pattern. The largest, densest concentrations were all in areas of the water where straw anti-erosion matting had been inundated.

This got me to thinking about stuff I had read in this old gem of a manual:

Book Review: Culture Methods for Invertebrate Animals (Lutz et. al.)

I got to thinking that perhaps the daphnia were congregating near the straw mats as the straw supported a healthy community of various live microfoods daphnia thrive on. remembering that boiled straw (and various farm animal dungs) were suggested as ideal culture media for zooplankton, I started experimenting. I didn't use dung as i need that for my gardens and planting beds...

I used six of my large Sterilite tubs (48 quart talls). Filling each with a mix of dirty tank water and rain water, I placed three outdoors in full sun (the conditions I find the most daphnia in) and the other three down in my critter cave under 12/12 hydroponic lighting. Floating tube type thermometers were used. Each culture had a roughly 10 oz handful of live java moss added. Dirty tank water was added as needed to all cultures to deal with evaporation.

All cultures utilize the same aquatic substrate a mix of crushed oyster shells (the type used in chicken husbandry), dirty tank detritus, and an aquatic compost of maple leaves (which I make myself here for breeding certain soft water fish). Old storm window screens recycled from when I had to update all the windows in my house were placed on top of the outdoor cultures to keep mosquitoes and chironimids out of the culture water. I also dropped four adult ramshorn snails into each culture as for me their presence seems to make for better cultures.

Containers A,B, and C are outdoor; 1,2, and 3 are indoors. Outdoor water temperature averaged 85F. Indoor water temperatures averaged 68F.

A and 1: Standard culture. filled container and added roughly 250 daphnia. Fed every other day with a yeast/spirulina mix I modified from (I believe this is where I stole it from...) Jennewt's recipie.

B and 2: Control Culture started with 250 daphnia and left to its own devices.

C and 3: Started with rioughly 250 animals. Cultures fed nothing but handfuls of rodent alfalfa straw (which is what I have on hand as my daughter is obsessed with rodents...)


The results after running these cultures since May has been stunning. The standard cultures A and 1 crashed every few weeks and had to be restarted. Largest yields from A and 1 were experienced at first. After the first month of the straw decaying in the water, cultures C and 3 produced yields comparable to the standard cultures with the added advantage of not crashing completely. I should note that culture C outperforms all others producing more daphnia than I could use. Extra daphnia were transferred to cultures 2 and B for holding. These cultures have since been converted over to the straw method.


Seeing that rotting straw water supported just as well if not better than the standard method, I decided to dig out my microscope and compare water samples from the straw cultures, standard cultures, control cultures and ten samples from various wild sites. After a long afternoon today, I found my suspicions were correct.

based on the number of microorganisms I attempted to count from roughly 1mL samples, the live bioload in the straw cultures and the wild cultures left all others behind. In attempting to compare wild samples to my farmed cultures, I believe the farmed cultures were superior to the farmed.

I will note counting was based off of the numbers of moving things I marked down. My microscope is a battered old thing rescued from a dumpster outside a certain college, and all my well slides are home made. I utilized a bit of sheer nylon cloth with a comparatively open weave as a net to hold critters in place and make them easier to count. There was also tons of stuff in there that could have been inert matter, or non-moving algae. therefor none of my numbers are very relevant given my complete lack of knowledge of such procedures.

This is all merely based on untrained observations by yours truly, but I have decided to convert all my cultures over to the straw method. Oddly enough, I could not see any difference between the indoor and outdoor straw cultures which leads me to infer that temperature was not much of a factor. But given the crude tools and methodology I employ, I suspect that the outdoor culture with its higher average temperature may actually produce more than the indoor. Given the wild variations of evaporation, weather and lighting outdoors, I am unable to give any valid conclusions on effects of temperature and lighting at this time. I would need to experiment further to do so.


Well, it is what it is. If you are looking for an alternate culture media for daphnia, I highly recommend the straw method. If you do give it a try, let me know how your results came out. I am curious to see if this is Johnny's Dumb Luck factoring in, or a real repeatable possibility.

The good news from all this is I no longer have to keep large yeast cultures in the fridge which means my poor wife has one less thing to give me the look of death for...