[ originally posted Oct 29, 2008 @ 12:33 ]

I came home to even more dead fish in my fish tank. I’d lost a few fish the previous night, and I was still upset about the incident.

At first I thought the fish were being violent toward each other, which didn’t make sense – all the fish in the tank were known to be peaceful species. I did see one rainbowfish nuzzle (or even nip) at another, however.

So I began to do a water change, and I came across a disgusting bug-like creature at the bottom of the tank…

WARNING: large picture of a bug

It turns out that this bug was one variant of a dragonfly nymph: a nasty creature that gets into tanks through eggs left on plants, or in bags of live food.
Dragonfly nymphs are nasty because they kill small fish and shrimp, all the while camouflaging itself and acting like a coward. The problem is, they grow to the stage where they can kill fish rather quickly, and then graduate to harmless dragonflies slowly.

The first thing I did was suck this one up through a gravel cleaner. As evil creatures always do, it put up a fight after pretending to lie dead. I decided to flush this one down the toilet, rather than killing it, for no logical reason.

I went back to dispose of its victims, and decided to check the gravel for more bugs. I’d read on a message board somewhere that dragonfly nymphs usually come in groups, so I had to make absolutely sure there were no more.

After spotting another one – a thin, brown-coloured bug – I uprooted all the plants and quickly transferred the remaining fish to another (ill-prepared) tank. From the slow and thorough process of “combing” the gravel with a fish net, I’d taken around six of these nasty brown bugs out of the tank, set fire to them and flushed them down the toilet.

The disturbing thing is that I’d seen the first nasty creature in the tank several days prior to the incident. I didn’t know how it got there, and as far as I knew it was dead.

The really amazing thing, however, was the lack of information online about how to remove (or more suitably, destroy) dragonfly nymphs. There was all the usual info about what they do to fish and how they get in the tank in the first place, but there are no products for treating them or documented methods of removing them.
In fact, there was far more information on their life cycles, and even people talking in message boards about keeping them as pets, than the fact they were pests.

It reminded me of a certain person at university whom I’ve had personal issues with. (They know who they are.) I knew how evil, vindictive and malicious – and also incredibly dull -they were, yet people actually liked them and thought they’re the best thing since sliced bread. It’s kinda disturbing how that happens, especially when you consider what unspeakable acts they’re capable of.

If you don’t want this to happen to your fish tank, make sure you wash your plants thoroughly before adding them, no matter where you get them from. It’s likely you’ll get some snails anyway, but it’s better to be safe.
But also check bags of live fish food for “additions”. In a bag of daphnia I bought once, there was a harmless red worm, but also what turned out to be a mosquito larva. Both are fish food, but there could have easily been something more deadly.