Mites: Is this too strong?

[Leenknegt-Lioen]

Hi,
I've bought a permethrin (is this the same as pyrithrin?) spray, with 1%
active ingredients for fleas in cats and dogs. Is this too strong? The only
other option was one with 0,25 %.
It sais: *"for cats under 2,5 kilo, 20 sec spray". What would that be for a
         gerbil?
        *"dangerous for aquaria and birdcages, lethal for fish, avoid
         contact with skin", I'm afraid it is too strong, but it seems
        like the only option.

I'm really new to this, so any help is greatly appreciated!
Sarah