Sick fish?

Greetings everyone. Hope everyone is well
I recently recieved some blue guppies from a friend...they have been in the tank for 2 weeks now..today I moved them into a different tank with the same water,gravel,filter plants ...and did a small water change ..soon after my one male started wiggling around weirdly with its mouth open..
Temp of tank is 25c
Sponge filter provides aeration..

Could it be stressed ?
Tank has been running for 5months now
I don't test my water ..I use my 3 senses..water did smell abit stinky but did a water change . I add sechem prime to my water a day before it goes into the tank..
Any help will greatly be appreciated.
Thx in advance

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Stinky how? Is it an ammonia smell (rotten egg), or an earthy smell?

 

Rotten egg smell would be sulfur.

 

Abit smelly like a normall tank without a water change for 2weeks.. kinda like a rotten egg..

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Do you think its ammonia poisoning or stress ?

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When you say "I moved them into a different tank with the same water,gravel,filter plants" - does that mean you moved all of those things along with the fish into the other tank?

 

Were there fish in the other tank already? Was there a filter running etc?

 

Yes.i they where originally in a tub for 2weeks now they in a tank


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It was just the 3 of the males .filter heater everything was running

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Some sulfur gas might have been released when you disturbed the substrate. You might need to do a large water change to be safe.

 

Oh,ok.so that could have caused the one male to act like that ?..ammonia poisoning

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