This is just my opinion.

Collecting live critters from the wild as food is a great way to introduce god knows what to your tanks and wipe out your fish stock. You are better off with frozen.

 

I have not done this but I believe going after dark with a flashlight will yield amazing results.

Also, if you just want mosquito larva, a bucket of water in your backyard works nicely. Just monitor mosquito spraying.

They spray Naled in my city. Naled is mostly insoluble in water and when in water, it is broken down in 2 days. It is moderately to highly toxic to fish. That said, the concentrations they spray at are not enough to affect fish and again, not water soluble. Birds would be dropping out of the sky before my fish would have to worry about live food I collect. I have had no issue using larva collected in my yard during seasons they actively spray.

Naled
https://www.epa.gov/mosquitocontrol/naled-mosquito-control

 

I collect earthworms and chop em up

I have a small worm farm for that.

https://www.bunnings.com.au/reln-garden-inground-worm-farm_p3160041

 

I haven't heard of anyone collecting daphnia for years. Way back when I did collect it a few times. I also knew a few people that bread fish that went almost every week to collect it.

Typically you want water that is bad but not too bad. Think in terms of a stagnate pond or a marsh. When daphnia is really in season, it can really be thick, sort of like how live brine shrimp are when the sell it to you. Even if you can't see anything it's worth running a net in a figure 8 pattern and see if there is anything there. If things are just right, you can get a mass of daphnia in 15 or 20 min, but you may not be so lucky.

If you have access to a copy of Exotic Aquarium Fishes by William T. Innes there are a couple of pages on the collection of daphnia in the fish foods chapter. A little bit of the book is a bit dated, since it was first published in 1935. If you or anyone else are interested and can't find the book, PM me and I'll see if I can scan the pages and post them or email them to you.

 

I had to cancel the trip because there's a threat of rain and it's 50 F outside... @DaveK, so the lake we're visiting is only called a "lake" because it has a whole lot of water in it right now, it dries up for most of the year, and there's something about an endangered salamander species and vernal pools...does this sound about good for daphnia collection?

Thanks for all the help everybody! While my friend and I have been contemplating culturing microworms, our fish are too small for earthworms...but if I ever get large cichlids or like an arowana, I'll keep this in mind! Pity that California banned stingrays...

Hmm.. @NickAu, even though I definitely agree with your opinions on frozen vs live...it's just not a feasible option for us at this point in time, due to lack of reasonable refrigeration (I refuse to stick frozen fish food in the communal fridge. that's just...not good etiquette). What type of nasties did you have in mind? Disease? Parasites? Or...well, I guess you could get just about anything from a lake... but I also think that it's useful to go back to our roots as well; from what I understand, back when fishkeeping was actually very very new, the old people would just go collect what they could to get their fish to eat...and some would go after tubifex-shudder * , I'm on my way to fish crazy, but I don't think I'm there just yet.

 

You could try the "lake" and see. It's been many years since I tried collecting daphnia. Worst case is you don't find any.

Consider setting up a white worm culture. You can keep them in a couple of plastic shoe boxes. They are about the size of black worms.

 

I'd still try it . Just look out for salamander eggs . The ones I've encountered were in gelatinous masses . You sure don't want to mess up the breeding of anything endangered . Anyway , if you don't find daphnia , you still might find bloodworms , cyclops , glass larvae ( might be too warm for these ) , and all sorts of bug larvae that resemble mosquito larvae but aren't . Just remember that some of this stuff can develop into things that are REALLY nasty ( water tigers , dragonfly nymphs , that sort of thing) to the occupants of your tanks , so feed sparingly and watch to make sure everything's eaten before feeding more .
I'm old enough to remember going out to collect tubifex when I was a kid . Some days you'd get a lot , other times you got nothing . But you had to rinse them out really well . I usually waited a day or 2 for them to flush out before feeding .
Until recently I had a couple of places for daphnia and cyclops , but one got drained and I'm leery of the other due to spraying for West Nile .

 

If you want to get scientific about it check the lakes carbonate hardness and dissolved nutrients with a test kit. Most time the best Daphnia comes from little ponds that drain from farms with moderate carbonate hardness and nutrient rich water.

Daphnia feed on suspended and free swimming micro algae. The big problem with wild caught is there are often as not, bad actors swimming among the Daphnia. Like Predaceous Water Beetle larvae, Water Boatman, Damsel and Dragonfly nymphs, various planarians, and disease organisms. The best strategy is to get a Plastic stock tank 'water butt' outdoor pond, which you can inoculate with your own Daphnia, that you know are free of bugs and bad actors. A transparent cover or Visqueen over the top will keep out the transient insects. Fertilize the stock pond with a cup or so of rotted manure and some oyster shell a few weeks before adding the Daphnia. It should develop a nice soup of algae for them to feed on.

 

What type of nasties did you have in mind? Disease? Parasites?

Yes to both of the above.

 

If you can't see anything, just start scooping cups of water from near the bottom of the pond and pouring them into a flat white pan. Unless you're collecting next to a Dupont factory, you're all but guaranteed to find individual some daphnia this way. It's not as efficient as other methods described above, but it's a last resort. Remove them to your to-go container using a pipette.

 

Set up a kiddie pool outdoors, before long it will be filled with water life to feed your fish with.

 

If you can't see anything, just start scooping cups of water from near the bottom of the pond and pouring them into a flat white pan. Unless you're collecting next to a Dupont factory, you're all but guaranteed to find individual some daphnia this way. It's not as efficient as other methods described above, but it's a last resort. Remove them to your to-go container using a pipette.

I am sorry but this is just bad advice, Remember you are dealing with peoples fish and while it may be OK 999 times, the 1000th time it will wipe out somebodies fish stock.

My fish are my pets just like my dog or cat are, and there is NO WAY I would do something that could cause them harm.

 

Ugh...I so wish that I could set up something like y'all are describing...but I'm in college, and space is a commodity that I'm lacking in. If I had the space...I'd do it in an instant, but I don't. Speaking of colleges: mine has a copy of exotic fishes by Innes. And holy [censored][censored][censored][censored] I freaked out, thanks for the rec Dave!

 

Just put a plastic tub in the windowsill if you can't put something up outside, leave the window open, and stuff will find its way in there.

 

I have no windowsill...and the windows have bug screens: I have no intention of ever removing them because the crane flies here are...well, ginormous is a bit too small of a descriptor, and I don't do grasshoppers...