Hyalella azteca culture

[Jesper]

I am looking for info regarding care for this species, I am hoping to make my culture a bit more efficient.

I have a small tank 15l or so with a bare bottom, a small sponge filter and a few Egeria densa, I am looking for info on how many light hours per day, how often to feed and how often to change water.

My colony gets 9h of light or so per day, temps are around 21C. I only feed a small amount once every week or so if they have finished what was left last week. Water is added every now and then from another tank to cover evaporation. I rarely do water changes as the colony is not large in relation to the volume of water.

Any advice welcome:happy:

 

[Jesper]

A small update... I have raised the temperature to about 25C and this have as expected raised the activity in the tank as well as the mating I have been able to observe.
Another reason for the activity might be that I added a few Egeria densa not long ago and it turns out these guys are ferocius plant eaters.... They are constantly eating the leaves of the Egeria densa plants....

A sidenote is that they love sponges with pores large enough for them to creep into...
I have a bit of sponge in the tank and it is used as a nest, dozens of them in there at any one time.

 

[Jesper]

I have also increased the lighting to 12h.. Also the sponge I mentioned is not the filter sponge but an addition piece of sponge..

I am sure we have a number of hyallella keepers around, share your wealth of knowledge!
They seem to make good larvae food and are easy to keep..

 

[Jesper]

I have not been feeding enough clearly... I added some frozen artemia to their tank while feeding newts yesterday. I thought I added too much... 24h later it was all gone and the hyalella were highly active...

I found a good guide btw...

Hyalella azteca • Deutsche Killifisch Gemeinschaft

 

[Jesper]

Well this has become somewhat of a monologue....

Anyway, the hyalella is doing great.. Their numbers are increasing rapidly and they eat loads..

The main things seem to be..

1.They seem to do much better when fed nutritious items. I have tried all kinds of vegetables but the colony really took off after I started giving them artemia and dried gammarus(yes...virtually cannibalism..nevermind}. They also tend to eat much, much less live plants when fed this way.

2. Make sure the water contains plenty of calcium for their shells, otherwise reproduction rates will go down.



A little bird told me that these creatures cannot break down lignin and cellulose and that they therefore cannot metabolise plant matter..What they do metabolise well is bacteria...So they chow decaying matter to get to the bacteria detritivores.

I have seen these guys attack live and healthy plants so they got to get something out of this behaviour...

Oh yes I have also seen them attack and eat snail eggs and I imagine that they would attack both newt eggs and larvae if they starve and are present in numbers..

These creatures are ridiculous efficient at locating food compared to other creatures I have cultured, seem to find things within seconds even though the colony is not very densely populated at all. Only thing that I have seen that can compete with that is copepods, which coincidentally inhabit the same tank...

 

[Yahilles]

I keep mine in pondtype tanks without any filtration, lots of debris on the bottom (based on fine limestone gravel), lots of dead leaves, willow and phoenix moss which they don't eat and i used to feed them fish food, pieces of fruits and hair algae i collect in other tanks. They really love eating this kind of algae (also rhodophyta and cyanobacteria), same for dead leaves. I haven't tried frozen artemia yet. They eat dead plant parts and java moss (they leave leafless branches of it).
Mine don't eat neither snail nor newt eggs. There are tons of bladdersnails in my culture, and i also raised newt larvae from eggs to morphs in Hyalella cultures.

 

[Azhael]

Can you confirm that their non egg eating behaviour is maintained? I´ll take your word for it, i just wonder if this is something you have consistently observed, or if they eat the odd one that may pass unnoticed. I´m terribly interested in culturing this species of gammarid and other than the possibility of them eating my plants, what worries me the most is them eating newt eggs. If you can confirm that for you they don´t (and if you could let us know for how long you have had H.azteca) that would be great news.

Jesper, i´m glad to hear they are doing better for you If you could upload a picture of the tank where you culture them i´d be thankful.

 

[Jesper]

Yeah, I have had snail breed in my hyalella culture so I do not think they have a preference for eggs of any kind, I assume aquatic eggs contain some kind of substance that repel small aquatic creatures... Otherwise not a single egg would stand a chance seeing that eggs must by their nature be highly nutritious.

I have seen the hyalella sit and nibble at snail eggs but they do seem to stop rather quickly, they have never consumed the eggs themselves just nibbled at the "gel" that surrounds the eggs...I think the eggs hatched anyway...

I wouldnt worry about the hyalella eating eggs, plants are another matter but as long as you dont starve them they seem to prefer decaying plant parts and detritus in general and even more so highly nutritious foods. I havent seen them eating live plants at all since I started stealing from the newts food supply to feed the hyalella.

 

[Yahilles]

Rodrigo, i recently put this year's first eggs in a pondtype set up for larvae raising which is already a hyalella culture, i saw them 10 times walking around the leav with the egg and the embryo is developing in peace.
I also released quite a bit of them in two adult newt tanks - they DON'T eat the healthy plants. I know they survive there because i sometimes see single specimens but they don't eat neither algae nor plants in the aquarium.
Jesper: The fact they walk on something doesn't mean they eat it.
Here's the photo, you can see little scuds around (long line on the left is a big scud and a moony shape on the right is a smaller scud):

 

[Azhael]

Thank you, much apreciated. It´s reassuring to see that the eggs are unscathed.
Oh Hyalella, we will meet some day.

 

[Jesper]

Nice photo, I was talking about snail eggs though and the hyalella was frenetically doing something to the sac which in turn was damaged after it left... Draw your own conclusion...
The hyalella had virtually been starving for a month at that point though.

I just dropped some c.o. larvae in with some hyalella, do you let the eggs hatch in with the hyalella wo any problems? I am a bit concerned about the hyalella adults attacking the larvae, they are certainly too big for the larvae to eat. I am counting on the larvae to eat the hyalella young. They are currently under observation:smile:

 

[Yahilles]

I said previously i raised orientalis from eggs in a tank full of hyalellas and i am doing the same now. Larvae that start feeding eat the smallest hyalellas and switch to older ones as they grow, simple. Here's what i saw today, it made me doubt:

But i left it be and some hours later the egg was without a scratch. The scud might have been eating micro algae that start growing on egg spheres? I don't know.
I tried giving mine frozen artemia and i didn't see a single scud around it (just snails), i also don't see them gathering over algae as they used to, looks like a dirty pondtype tank gives them enough food that they don't need to pile up over anything eatable that shows in the line of sight.

 

[Yahilles]

Hey, a little update for people interested in using "aztecs" as food for larvae:
The little orientalis have hatched in the tank and they seem to be doing just fine with scuds, i didn't see any of them being attacked or eaten by amphipods.

 

[Jennewt]

Hi Jesper, how do you feed them dried gammarus? Do you powder it, or just throw in whole dried?

 

[Jesper]

Janusz:
Hey, I think it all depends on density of Hyalella. IMO the hyalella adults are capable of attacking larvae. I have raised some H.o. larvae in a naturalistic tank with Hyalella etc in it with no problems with either eggs nor larvae.

However when I put larvae in the breeding tank of Hyalella the larvae started to die within hours, so I had to remove them... Obviously the breeding tank is full of Hyalella, at a certain density it would seem some species start irritating attacking larvae.

I have had the exact same result with Copepods, in a naturalistic tank with a moderate Copepod population no problem whatsoever. In a Copepod breeding colony deaths within hours. Obviously some species of Copepods are capable of attacking larvae at high densities.

I figure that these kind of attacks are unnatural and only come about by introducing larvae to unnaturally high densities of these species. Daphnia is a safe bet if one wants to present a large amount of feeders to larvae (assuming the water parameters are kept in check).

Jen: Yes, I threw them in whole to both shrimp and Hyalella. They will just attach themselves to the floaters and eat away.

 

[Jesper]

An update... My Hyalella colony has retired, I found that they were hard to breed in high densities and also quite sensitive to environmental changes in the end(I move a lot).

I have since made yet another try at Daphnia with success....very strange considering multiple failures in the past. I now understand why so many ppl culture them...finally...

I also started culturing Asellus...I'll post that in another thread..