Crangonyx as an algae eater

[dw1305]

Hi all,
I don't think I have any "Northern River Shrimp" Crangonyx - <"Live food culture - Crangonyx pseudogracilis"> left in the <"tanks with fish">, but I have a "spare tank", until it goes to @megwattscreative, with plenty present and I tried putting a Frogbit (Limnobium (Hydrocharis) laevigata) plant, with some green algae on the roots, in with them to see what happened.

This is the result:
Before

After

So I'm looking on that as a success.

Cheers Darrel

 

[Ratvan]

That's a pretty drastic change, over what time period was this?

 

[dw1305]

Hi all,

That's a pretty drastic change, over what time period was this?

I'm going to say ~72 hours, I just meant to leave it in overnight, but my wife and I both have COVID at the moment (unfortunately it is still a "thing") and I just forgot about them.

I thought of doing it because I had some Frogbit that has been <"sitting in a bowl and has algae">, and I'd moved some moss and Susswassertang (Lomariopsis lineata) into the tank and noticed that it rapidly had Crangonyx all over it. I couldn't see what they were eating (diatoms perhaps?), but they were definitely eating something.

cheers Darrel

 

[NathanB]

Wow they did a brilliant job, I remember setting up a small native invert tank with some algae covered rocks that I collected from the local stream, I also added some duckweed from my pond that was covered in a few Asellus sp. I watched as some larger "scuds" grabbed a poor little water louse and started to eat it! Never properly identified them but my guess was maybe a Gammarus species. Have you ever experienced anything like that with amphipods Darrel? Im not so experienced with them apart from that and one of our native saltwater species, but I only occasionally get a glimpse of one creeping between some smaller rocks once in a blue moon.

 

[Bradders]

my wife and I both have COVID at the moment (unfortunately it is still a "thing") and I just forgot about them.

Get well soon. (Although the forced plant focus might be of some consolation!)

 

[dw1305]

Hi all,

Asellus sp. I watched as some larger "scuds" grabbed a poor little water louse and started to eat it! Never properly identified them but my guess was maybe a Gammarus species.

I think that Hyalella azteca and Gammarus spp. are a lot more omnivorous than Asellus or Crangonyx, which are detrivores. From - <"https://invasions.si.edu/nemesis/species_summary/95082">

..In Northern Ireland, predation by other Gammarus species (G. pulex, G. duebeni, G. tigrinus, in descending order of predation rate), limited the distribution of the smaller Crangonyx pseudogracilis (MacNeil et al. 2003).

Personally <"I've not tried Hyalella">, and Gammarus ssp. don't last at tropical temperatures.

,Have you ever experienced anything like that with amphipods Darrel?

No, but I still have nightmares about potentially introducing the <"Killer Shrimp"> - Dikerogammarus spp - <"https://www.nonnativespecies.org/assets/InvasiveFWShrimpsIsopods.pdf">

Cheers Darrel

 

[dw1305]

Hi all,
I put another Frogbit plant in, much less noticeably green in the root department, but this was about 10 minutes afterwards.

Apologies for the quality of the photos.



Cheers Darrel

 

[RickyV]

@dw1305 Do you know their rate of reproduction? Brood sizes and time to reproductive age? I have a bunch of these in my tank at home that I want to use to make a culture for 3000 Liter High Tech Planted Tank I'll probably make a culture connected to the main tank flow like the blackworm cultures. But I'm wondering if they reproduce fast enough to be worth culturing.

 

[dw1305]

Hi all,

@dw1305 Do you know their rate of reproduction? Brood sizes and time to reproductive age?

Quicker than Asellus, but after that I don't really know.

Because they are used for aquaculture and as a bioassay organism (as well as being an invasive) I should be able to find some figures.

..... But I'm wondering if they reproduce fast enough to be worth culturing.

I think they do.

Cheers Darrel

 

[Gill]

Cool little things aren't they, they were a permanent resident in the filters at Coalville.

Rest up and take care, A few of the engineers lost toe nails with this covid, they just fell off.

 

[dw1305]

Hi all,

I should be able to find some figures.

These are for <"Crangonyx floridanus">, but it is morphologically and ecologically pretty much identical to <"C. pseudogracilis">:

<"Reproductive Biology and Adaptability of the Invasive Alien Freshwater Amphipod Crangonyx floridanus (Crustacea: Amphipoda, Crangonyctidae)">.

cheers Darrel

 

[Little]

I adore your dedication to science and the coupling of free and effective aquarium solutions… but… man those things look fugly.
It’s like hairless cats to avoid fluff on the sofa 🤣

 

[dw1305]

Hi all,

I adore your dedication to science and the coupling of free and effective aquarium solutions… but… man those things look fugly.
It’s like hairless cats to avoid fluff on the sofa 🤣

Get away with you, Crangonyx are quite cute, although that maybe doesn't show in the picture.

Asellus are possibly a bit more <"aesthetically challenged">.

They are both definitively hairless.

Cheers Darrel

 

[Bradders]

Striking resemblance?

 

[simon_the_plant_nerd]

@dw1305 Did you send me some of these a while ago? I have a lot of beasties from you living in my shrimp tank but I don’t think I have these. I’m tempted to change my main tank from high tech to medium tech and see if I can get more diverse life living in there. Seems to be positive and I quite like ‘ugly’ creatures.

 

[dw1305]

Hi all,

@dw1305 Did you send me some of these a while ago? I have a lot of beasties from you living in my shrimp tank but I don’t think I have these.

Yes, I'm pretty sure I sent some to you. They are hyperactive, so if you had some left you would probably know.

Cheers Darr

 

[dw1305]

Hi all,

The species I assume to be hyalella azteca, although they were just sold as 'mini scuds' on ebay, are not only omnivorous and great algae eaters but aggressively predatory

You need to look at <"their urosomes">.

cheers Darrel

 

[dw1305]

Hi all,

There must even be quite a lot of them if I can always see them but I've still never once seen a baby or intermediate size crangonyx other than when I introduced the original 12 which were a mixture of different sizes. @dw1305 do you also find that the small ones remain completely hidden until they are adults? or do you also see them swimming around?

All sizes swim about, which is probably why they don't tend to last with any micro-predators, however small.

There's a really ridiculous amount of palces for them to hide between loose gravel and heavily drilled lava rock so based on the fact I can always usually see at least four scooting about I assume there's probably dozens living in there by now but despite really looking I've seen them mating but not a baby even once.

Try a bit of cooked vegetable, something with some colour (Green bean would be ideal), and all sizes will probably accumulate on it.

cheers Darrel

 

[dw1305]

Hi all,

Seems the only food that gets a reaction out of them is bacter ae, they ignore my diy gel food and other commercial pellets but they seem to get a lot more active when I feed some bacter ae just like the other shrimp.

They like cucumber.



Cheers Darrel

 

[ScareCrow]

I think they may also eat black beard algae. I was going to post back in the summer but didn't have an opportunity to test if it was Asellus or Crangonyx that ate the black beard algae. The container I placed the black beard algae covered plants contained both species. After a few days the black beard algae had been completed removed from the plants though.