# Fish flashing on water change



## DKRST (Jan 11, 2011)

I noticed that my fish "flash" right after I make a 20%+ water change. I don't have a good test kit (yet), but is that a sign of anything in particular regarding the tapwater chemistry? 
My dip-stick test indicates everything's normal (no elevated ammonia or nitrate/nitrite)l, pH about 6.8-6.9, but from posts here, the test sticks don't seem particularly reliable.

No sign of disease, no new fish in tank.


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## lorax84 (Nov 3, 2010)

What I think you are referring to is normal. Flashing is typically a mating behavior that can be triggered by water changes. Most fish mate during the rainy season in the wild and water changes can simulate fresh rain.


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## bettababy (Oct 12, 2006)

That's not a question easily answered, especially not via internet and without reliable test kits. Get liquid test kits for ammonia, nitrite, nitrate, pH (API makes a good kit for a reasonable price). When you are ready to do a water change, test the tank water AND the tap water, compare the 2 before you actually do the change. If there is a big difference in anything from tank to tap, make sure the water changes are small and frequent instead of large and infrequent. 

What you describe as "flashing" could be a number of things, between actual flashing to attract a mate to physical effects of a water chemistry swing. It is quite common in many species that a swing in water chemistry can trigger spawning behaviors. Large swings in pH, ammonia, nitrite, and nitrate can also trigger shock to the organs, which can cause anything from a "twitching" type of reaction, to heavy breathing, to near instant death. Lots of possibilities that can't be determined without the ability to see what happens and run the needed tests just before, during, after, etc.


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## lindsayletcher (Mar 23, 2011)

DKRST said:


> I noticed that my fish "flash" right after I make a 20%+ water change. I don't have a good test kit (yet), but is that a sign of anything in particular regarding the tapwater chemistry?
> My dip-stick test indicates everything's normal (no elevated ammonia or nitrate/nitrite)l, pH about 6.8-6.9, but from posts here, the test sticks don't seem particularly reliable.
> 
> No sign of disease, no new fish in tank.


Is the water the same temp as the tank? It doesn't sound worrisome to me.
_Posted via Mobile Device_


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## DKRST (Jan 11, 2011)

Finally got an API test kit, had elevated ammonia. Increased water changes, decreased feeding, problem fixed for now...


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