Shrimp behavior

[Phlegethon]

I have a 5.5 gallon desktop aquarium with some Amano shrimp (4). I change the water every Friday. So today after I changed the water my shrimp started swimming around like mad, around and around they go. Is this normal? The new water was the right temp and de-chlorinated. I did notice yesterday that my nitrate readings were a bit high (20ppm).

I've also noticed them doing strange things like riding "piggyback" on each other and doing something that looks like fighting. Very hyperactive. They're small (<1"). The 2" Amanos I have at home are lethargic by comparison...

 

[krap101]

could be ammonia or something else

 

[Phlegethon]

Nitrite & Ammonia are both 0ppm. They only started this after the water change. Now they appear to be chasing each other in circles...weird. Maybe they are "happy". LOL

 

[krap101]

maybe their mating... theres someone in here that has baby amanos (had them breed) and maybe they can suggest something