Problem after water change???

[Freezers]

Hello my dear friends before 2 days I did water change as usual but this time I ad just a small dose of salt because I see some damage in my piranhas from fighting and 1 of them scrub in gravel.
What I see 2 days now is a almost scared group take a tetitory each to defend and not playing, swimming or anything like the normal and great behaviour that I was having not play with my fingers in front of a glass and many other things that I don't like... Last day they don't move at all each of its place...
So I am thinking to make another water change to take tha salt out of gravel tomorrow or today with same temperature and bacteria and contitioner water but I would like to ask you is it possible or we will run more problems since I will change almost 40% in total and not 20 25 as I always do?
Is osmotic stress possible or kill any beneficial bacteria or stop eating again?
I already have a fully cycling sponge filter.

 

[Rocksor]

We need water parameters, measuring using liquid test for ammonia, nitrite, nitrate and ph.

 

[Freezers]

We need water parameters, measuring using liquid test for ammonia, nitrite, nitrate and ph.

Nitr, nitra I don't know at the moment but before 1 month it was very good
Amonia always 0 thanks God
Ph 6,5 6,7
Temperature always 25 26.
My water was never a problem to be honest maybe it's the area it helps but always I was having perfect conditions

 

[Freezers]

Any advices?

 

[Rocksor]

How long have you had your piranha?

 

[Marximus]

Sponge filters are not good enough for piranhas, u got 5 u need atleast 125g tank for those. And I’m terms of not moving.. eventually as they grow older piranhas tend to hover in one spot most of the time.. they are shoaling fish not schooling. So they tend to have little spots as territories. Piranhas are more fun when young more interactive but as they grow old they become more sedentary.

 

[1 2many]

A 40% water change shouldn’t be a problem. If anything you might want to consider doing higher percentage water changes from now on.
How much salt did you dose?
And as Rocksor already asked what are your water parameters? There could be a problem with your nitrate level.

 

[Freezers]

How long have you had your piranha?

A few months and never have problem with them it's very nice and happy group.

 

[Freezers]

Sponge filters are not good enough for piranhas, u got 5 u need atleast 125g tank for those. And I’m terms of not moving.. eventually as they grow older piranhas tend to hover in one spot most of the time.. they are shoaling fish not schooling. So they tend to have little spots as territories. Piranhas are more fun when young more interactive but as they grow old they become more sedentary.

I have it in 350 ltr tank its amazing group and healthy really with no territory stuff since I put in in the tank normally ylthey very happy with the space and swimming around all day its all more than 10inc end it's very active group but now these 2 days things its more heavy....

 

[Freezers]

A 40% water change shouldn’t be a problem. If anything you might want to consider doing higher percentage water changes from now on.
How much salt did you dose?
And as Rocksor already asked what are your water parameters? There could be a problem with your nitrate level.

OK my friend those are good news then tomorrow I will proceed on 20ltr water change just to take out off the salt.
I drop about 1 tea spoon it's very small amount for this 350ltr...
What you think?