To crayfish or not to crayfish?

[myswtsins]

Have you checked to ensure that your pond isn't getting any surface runoff running into it?
Your pond doesn't look like it has much of a berm to prevent that.

Pretty certain runoff isn't an issue but I guess there is no way of being 100% sure of that? We did slope everything away from the pond, removed all grass areas from near the pond and use only rocks or woodchips near the edges.

I can't add much to the discussion except to say we put four crayfish in our pond (@Faebinder - not sure what kind? Bought them at the same place we bought our koi) and we've seen them a handful of times since then. Make that less than a handful... maybe three sightings, total over five years time. I would have thought they were all dead except we saw one again last summer. I think they probably stay hidden in the rocks in the pond. Like you @myswtsins I wondered if they would survive the winter - we are zone 5 - but obviously they did. I would say your chances of catching them once you release them are slim to none. They are elusive little critters. As for eating the algae - not sure how effective that would be, unless you had an army of them.

I would suggest you try some watercress in your stream. Just buy it from your local grocery store - it's generally sold in bundles in the fruit/vegetable section. It doesn't need to have roots. Pull the bundle apart into stems and tuck a few stems every few feet into the rocks at the sides of your stream. Within a matter of days it will start growing - watercress LOVES flowing water. It's one of the best water filtering plants I've found. You have to watch it because the roots grow into massive mats that will collect loads of silt and debris. If it gets too thick, it will divert the water, possibly out of the stream. I pull out pounds of it every few weeks from my waterfall all summer long - it's amazing stuff. We add it to salads or juice it with other greens. Very healthy for you! Ours will even occasionally come back the next year if I leave a few clumps of it in the fall. But even if I have to replant it, it's a $2 investment every spring.

It's also really pretty - here's a picture of my waterfall:

See the sunbathing mermaid? Over her head and to the left of her is all watercress. Scale is a bit tough to tell - she's about 20 inches tall. There's a small pool behind all that cress fed by both the bog to the left and the small stream directly behind it. I had already pulled a lot of watercress out - it was slowing the path of the outlet from the bog causing a bit of overflow.

Completely off your crayfish topic I know, but hopefully another idea for you!

Thanks for the suggestion! And thanks for sharing your experience with crayfish. I do not expect to see them often, more like one of those extra exciting moments when you actually DO see them, so my expectations are on point in that area anyway. hehe I do plan to add some forget-me-not to the stream area next spring. Meant to do it this fall but they were still flowering and I couldn't bring myself to cut it down to transplant. lol Silly me, I know! Beautiful waterfall area btw.

myswtins, your algae has a vibrant green colour to it for someone that is not feeding the fish anymore. The nutrients to feed the algae have to be coming from somewhere.
Did you figure out what the oily residue was on the rocks?
The various containers you have that you submerged, what did they originally contain?

That picture was from before I stopped feeding to be honest. It did look the same after too so I never took more pictures. Oily residue? You must be talking about my pond construction thread from the gravel we added (and washed 1 shovel full at a time!)? It was very a very minor amount of residue and was gone with minutes of turning on the pumps. My lily pots were brand new "oil pans" from the dollar store, that I also cleaned with vinegar before adding to the pond even though they were clearly not used. Thank you for your time and extra effort digging through my original build thread!

 

[Priscilla]

I once put two wild crayfish in my fish tank - disaster. They used to try to climb out !!! !! More disturbing is seeing them climb up high to jump on the fish as the swam by to eat them. I don't know what size your pond or your fish are, I suppose if your pond is big enough it should be fine, and if your koi are big enough they may leave them alone. But that was not my case in the tank.

Good luck with whatever you decide.

One more thought, when I first started up my pond I got a lot of the string algae too, what worked for me was adding an aerator, I know in a stream that's more difficult, but I'm just saying what worked for me.

 

[Stephen T.]

We used artificial Christmas trees bought at yard sales for shade and background privacy around one of our ponds/streams a few years back. This sounds like a strange way to get shade, but very few people noticed they were artificial. They worked great and the birds flocked to them too. They won't hold up in sunlight for more than a few years, but by then trees you plant may be big enough anyway.

Steve

 

[seandelevan]

Stick some cuttings of various plants all along the stream. Since the water is running it will be almost like an Aquaponics set up. Virtually any flower or plant you want will root and start sucking up all those leftover nutrients that the algae is having a field day with. Algae gets out of control when there are no other plant competing with it. Out compete it with other plants.

 

[DELBOY]

I once put two wild crayfish in my fish tank - disaster. They used to try to climb out !!! !! More disturbing is seeing them climb up high to jump on the fish as the swam by to eat them. I don't know what size your pond or your fish are, I suppose if your pond is big enough it should be fine, and if your koi are big enough they may leave them alone. But that was not my case in the tank.

Good luck with whatever you decide.

One more thought, when I first started up my pond I got a lot of the string algae too, what worked for me was adding an aerator, I know in a stream that's more difficult, but I'm just saying what worked for me.

I think crayfish are evil things they will definitely eat young fish and they breed like rabbits,not even sure if you are allowed to put them in your pond in case they spead into nearby waterways

 

[Lisak1]

not even sure if you are allowed to put them in your pond in case they spead into nearby waterways

Definitely not the case in the US - our pond stores sell them specifically for pond stocking.

 

[bettasngoldfish]

I would not trust them with fancy goldfish (as the original poster stated are in the pond) because fancy goldfish tend to have longer flowing tails (which can make them a prime target) as well as them being slower swimmers and the fact that they tend to sit on or near the bottom while resting or sleeping.

Koi *may* be fine as they are much larger, have shorter fins and are much faster and stronger swimmers than fancy goldfish.