more dead shrimp

In the days following the first death, there have now been three more dead shrimp. And I've identified the killer.

Me. I forgot to add some food or other rotting material to the fish tank when I set it up to 'cycle' on its own for the first two weeks. In other words, sterile water was simply running through the filter without the establishment of the nitrogen cycle. That's what I get for having let ten years lapse since I last did this.

I'm now doing daily water changes and testing the levels of nitrite and nitrate. Happily, the nitrate levels are already non-zero, meaning that the tank now has the two forms of bacteria necessary to turn fatally toxic ammonia into relatively harmless nitrate (which is plant food).

Unfortunately, the bellwether shrimp are letting me know that I don't have things sufficiently under control. They are generally (very) active and seem to be eating well, but the appalling death rate (as well as the NO2 readings) tell me that I've got to step it up. I might just go to twice-daily water changes. I don't want to lose any more of the bizarre little critters. Or a fish.