Why does my tank smell like a rotting fish?

[Deep Blue Sea]

My 75g has this scent coming off it like a rotting fish thats been left in the sun, I checked everything
Ph - 8.0
Nitrites - 0.20
Nitrates 0.50
Amonia 0.50
I even checked under all the rocks to make sure nothing got stuck there and died, I also checked the filter which smelled just as bad but it had nothing out of the ordinary in it (I still washed it anyway). My last water change was yesterday and I did a 25% change. It only started stinking like this is in the past 2-3 hours, what could be wrong?

 

[convicts94]

same my room stinks like fish

 

[Nabbig2]

Hmmm, well if it smells like rotten eggs it might be anaerobic bacteria somewhere under the gravel. Did you stir the gravel or do anything to the tank in the past few hours?

 

[Deep Blue Sea]

Hmmm, well if it smells like rotten eggs it might be anaerobic bacteria somewhere under the gravel. Did you stir the gravel or do anything to the tank in the past few hours?

No, and it doesnt smell like rotting eggs it smells like a rotting fish, you know like when a fish jumps out of its tank over night and you wake up to that nasty smell

 

[Darth Scohin]

Do you feed Massivore? also you shouldn't have a Nitrite reading....add some Prime

 

[gangster]

well cycling ur tank would have helped....hope u dont lose any fish

 

[DaRKdan]

When you did your water change did you spill any chemicals? I once spilled a bottle of prime and the room smelled for days!

 

[Deep Blue Sea]

yeah I fed them like 1 massivore pellet today because I was hopping my sen would eat it, does it make you tank smell bad?

 

[Deep Blue Sea]

When you did your water change did you spill any chemicals? I once spilled a bottle of prime and the room smelled for days!

Nope

 

[Bazinga]

a bottle of beneficial bacteria broke in my stand once and i didn't notice until i opened it up, smelt horrible and god knows what grew