Mass Extinction in my pond...

[hotwheelsearl]

So I have had this fish pond for years now, and today just discovered a mass extinction event rivaling the PreCambrian...

Here's the story.  We have tons of fish of different species.  However, only 2 species were affected - the guppies and white skirt tetras have been decimated.

The goldfish, catfish, red platys, and silver mollies are just fine, however.

My theory is that something washed in the pond during the recent rains, but what would this be, and why would some types of fish be perfectly okay while the others are gone?

Nitrate, nitrite, temperature, pH, are all fine.  Hardness is fairly high, but it's always been like that and has never adversely affected the fish before (as in, we've never had a mass die off like this).

Sorry this isn't about koi, but any help would be greatly appreciated!

[Bob_A]

Good luck.

[dperry]

Like all diseases of animals and plants, fish diseases can be specific to certain groups of fishes, affecting one group and not others.  Look in that direction.  You might like to look at so-called Neon Tetra Disease (Pleistophora disease).  Flood-borne contaminated water could certainly have carried an infection from another area or watershed.