Red Cherry Shrimp behaviour

[Andrej]

Good Day

I noticed that all my shrimp, big and small gathered in one bottom corner of my 55 gal aquarium and are having some sort of 'union meeting'. Is it normal behaviour for shrimp for all of them to hang out in one corner, is it breeding thing? Usually they are all scattered around the aquarium. And they have more than plenty hiding space.

[Zoe]

Plotting your demise, no doubt!

Or perhaps some food bits have gathered there?

[lucius]

To add to Zoe's comment.  Maybe you have a dead spot from the filter and some food accumulated there.  Or they are hanging out there because of the dead spot.

[Andrej]

So next day I notice them doing the same thing , I did water quality check and saw that I has an amonia spike. Did 50% water change emediatly , vacuumed gravel and etc. After they were all back swimming around and being silly and all happy.

So that is just a warning signal I guess.