Crangonyx as an algae eater

[dw1305]

Hi all,

I'm not sure why they aren't more popular in aquariums but I suppose it's because you don't see them much.

I really like them, in some ways they are the <"perfect tank janitor">. They are more active at night, and don't swim in the water column, but possibly just because they <"lack aesthetic appeal">?

I introduced several at the same time I added crangonyx to my tank and I have seen one once in the same period that the crangonyx have either multiplied or become bold enough that I can see them scooting about almost all the time.

I think the "scooting bit" is why Crangonyx <"don't persist with most fish">, but Asellus do.

cheers Darrel

 

[dw1305]

Hi all,

It's still a bit of a puzzle to me given that H. azteca are widely known to become problematic pests even in tanks fairly well stocked with fish and they are only very marginally larger than crangonyx.

<"I've never kept"> Hyalella azteca - <"https://fishtankdk.blogspot.com/2013/01/live-food-hyalella-azteca-breeding-and.html">, but it would be an interesting comparison. I wonder if H. azteca are just a lot "crunchier", and that this might put some fish off?

I've seen studies looking at the interaction of other amphipods and Crangonyx sp. and it looks like Crangonyx are eaten by pretty much all the other Gammarus, Dikerogammarus etc sp., so I'm guessing you couldn't keep Hyalella and Crangonyx as a mixed culture, whereas I know that Asellus aquaticus and Crangonyx pseudogracilis can co-exist without any problems <"Predators vs. alien: differential biotic resistance to an invasive species by two resident predators">.

When I was keeping the crangonyx in a large glass jar they spent most of their time clinging to the glass eating biofilm but now they're in the tank I have never seen one anywhere other than substrate level and this may represent something similar but there's too many variables to tell.

I'd guess that is just <"where the food is">?

They have different colour morphs of Asellus in Russia just like we do cherry shrimp.

I've found out that they do lab. genetic work on colour morphs, so they maybe available more widely. This is a useful paper for Asellus diet etc. <"Frontiers | Building on 150 Years of Knowledge: The Freshwater Isopod Asellus aquaticus as an Integrative Eco-Evolutionary Model System">.

This one has some details for Crangonyx <"https://www.sciencedirect.com/science/article/pii/S1470160X2100025X"> "Leaf breakdown rates as a functional indicator were influenced by an invasive non-native invertebrate in urban ponds"

cheers Darrel

 

[dw1305]

Hi all,

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.

@Konsa found that Asellus eat BBA in <"Feeding a California Blackworm culture - Lumbriculus variegatus">.

I don't tend to have <"much BBA"> in the tanks, but I have a lot of different tank janitors, so "cause and effect" are difficult to pin down.

cheers Darrel

 

[LMuhlen]

How would one be able to acquire some of the animals mentioned in this topic, or others similar, in a distant country, say.... Brazil, as an example?

 

[dw1305]

Hi all,

How would one be able to acquire some of the animals mentioned in this topic, or others similar, in a distant country, say.... Brazil

Probably tricky for Asellus or Crangonyx spp., your best bet might be a University? Where they are interested in water quality?

Some Hyalella spp. are native to S. America <"https://www.tandfonline.com/doi/full/10.1080/01650521.2021.1964902">, so that maybe another option?

A further option would be to pyo by netting a local small weedy stream (or pond) and then trying to identify any crustaceans you find. This one could be very interesting, but leaves you open to collecting something <"monstrously carnivorous"> - <"Macrobrachium amazonicum - Wikipedia">.

cheers Darrel

 

[dw1305]

Hi all,

on whatever fills a comparable ecological niche in brazil!

There definitely will be a crustacean in the "vegetarian shredder" niche, finding a name might be more difficult.

cheers Darrel

 

[bazz]

I wonder if H. azteca are just a lot "crunchier",

They defnitely look crunchier.

There's only one way to find out!

 

[dw1305]

Hi all,

There's only one way to find out!

Personally I'd be more than happy to do the "raw prawn crunch test", but unfortunately I only have Crangonyx, which would disqualify me. Fortunately @louis_last has cultures of both species, so would be a much more qualified person for this ........

cheers Darrel

 

[dw1305]

Hi all,
Useful to know.

I don't know how much use this information is given that you can't maintain a permanent population of mayfly larvae in a tank but they do spend about a year as larvae and they can be bought in the UK from blades biological a lot cheaper than cherry shrimp or amanos. The tank they're in is heated to 22c and they seem fine at that temperature.

You would need the right Mayfly nymph, the <"Pond Olive"> (Cloeon dipterum) - <"What’s this?">.

The main problem would probably be the fish eating them, they are another <"cat-nip"> invertebrate.

cheers Darrel