140g

[Delphinus]

I'm not sure how rare it is, I think it's reasonably uncommon for the most part but having said that I seem to get about at least once a year. My clams are older and larger than average though, so it could have something to do with size and age.

Most of the times the event seems small enough but I did have a massive clam spawn about a year ago that spiked my system hard enough that I did lose fish, I think it was due to O2 depletion, the fish that died were all breathing/pumping very hard and heavy in their final moments. Not much you can do to prevent it, if it happens it happens, just be sure to keep your carbon clean, skimmer clean and be ready to do a waterchange if need be afterwards.