Here is a weird Hydra question

[GaryE]

I feed a lot of freshly hatched brine shrimp, so when Hydra gets in (as it always seems to) it does well. In my new house, I have a green version that seems to photosynthesize, and doesn't seem to sting much, and a paler one I haven't seen before, that does sting young fish but doesn't seem able to catch them. To me, you battle Hydra because you have to, but a 100% victory forever is likely. Like bigotry, superstition and greed, it always pops up again.

I spotted the pale one today, and am a bit curious at what I see. I spotted a tiny welt on a fry. I went looking. There were no visible Hydra on the plants, or on the tank walls. It's a bare bottom tank, and they weren't there either. But a piece of basalt rock about the size of the palm of my hand looked like a wheat field. Every possible spot on the surface was crowded. The glass all around the flat rock seems clear. I'll wager that 80% plus (I know it has to be scattered elsewhere - it's Hydra) of the beasts in the tank were on that one little island of basalt. It is very strange.

What's the attraction? It's speculation time!

I know how to knock off the Hydra without harming the fish. That isn't the question. But why the basalt...

 

[Sgooosh]

I feed a lot of freshly hatched brine shrimp, so when Hydra gets in (as it always seems to) it does well. In my new house, I have a green version that seems to photosynthesize, and doesn't seem to sting much, and a paler one I haven't seen before, that does sting young fish but doesn't seem able to catch them. To me, you battle Hydra because you have to, but a 100% victory forever is likely. Like bigotry, superstition and greed, it always pops up again.

I spotted the pale one today, and am a bit curious at what I see. I spotted a tiny welt on a fry. I went looking. There were no visible Hydra on the plants, or on the tank walls. It's a bare bottom tank, and they weren't there either. But a piece of basalt rock about the size of the palm of my hand looked like a wheat field. Every possible spot on the surface was crowded. The glass all around the flat rock seems clear. I'll wager that 80% plus (I know it has to be scattered elsewhere - it's Hydra) of the beasts in the tank were on that one little island of basalt. It is very strange.

What's the attraction? It's speculation time!

I know how to knock off the Hydra without harming the fish. That isn't the question. But why the basalt...

it may be that they like the rock since everything else is smooth, they can only anchor on the rock

 

[Colin_T]

The rock is probably where the first one landed and that is a good place to live with plenty of current and food.

The green hydra are often feeding on single celled algae.

Hydra usually spreads in plants. It can hide among Java Moss for years and you get outbreaks here and there. If you have hydra in one tank, you need to treat them all at the same time to get rid of them. then quarantine and treat any new plats to prevent re-infestation.

 

[GaryE]

I only really worry about Hydra in rainbow tanks - rainbow fry are not the sharpest survivors out there. I just assume they are always lurking and knock them out when they appear. They annoy the killies if I miss them, but...