Dying Amano Shrimps And Ancistrus

[coly]

Hello everybody!
I'll try to be as exhaustive as possible. I have a 70 liters (about 18 gallons) planted tank that has been running for 7 1/2 months. I had 4 panda cory, 2 dwarf gouramis, 6 harlequin rasboras, 2 zebra loaches, 2 ancistrus and 4 amano shrimps.
A couple of weeks ago one of the ancistrus died (I have to say that about 3 months ago another one died), then 2 days ago it was the time of one of the amano shrimps. Yesterday I saw another one with almost no "legs" and very "cloudy" inside. After a few hours she was dead.
I ran to the lfs and they said it was likely due to my high phosphates level... so these are my water parameters:

pH = 7
gH = 6
kH = 3
NO2 = 0
NO3 < 5 mg/l
PO4 = 5 mg/l

Phosphates are actually too high, but I thought they were a problem mainly because they trigger algae growth...
So now I have put a resin for phosphates reduction, but I still have some doubts. Since one of the amano (I didn't look very carefully at the other) was dying without legs, couldn't it be that the zebra loaches or somebody else are attacking them? It's a couple of months I have the zebras, but they spent the first month hiding and it's only a few weeks that they turned out to be "brave" and go around all the time.
Last thing: the only fish I've ever seen running after a shrimp trying to nip his tail was the female gourami
Any suggestion/help will be greatly appreciated!!!!

 

[-germ-]

My first thought before seeing the second part of the post was Dwarf gourami aggression.....
Theres not a great deal you can do, i'm know nothing about shrimp but like you touched on the fact the shrimp had no legs; is suspicious.
I'm no expert but i doubt high phosphates would lead to loss of limb?
Dwarf Gourami IMO are often alot more aggressive than people expect, in addition to their already territorial nature.

Careful observation should reveal the culprit, if indeed it is a result of aggression.

 

[coly]

Thank you very much for replying! I was out of internet for a couple of days.
What I observed is that of the two shrimps still surviving, one is getting more "orange" (which is the same thing that happened to the dead two, so I'm not confident at all...). Maybe some fish is attacking them once they are weaker... ut your hint about dwarf gouramis is very interesting. I was thinking if my female was the only one SO mean! Maybe she's overstressed by the male and that's why she's attacking other fish...
Thanks again!