What's living in my aquarium

What's living in my aquarium

Observation - What's living in my aquarium. Description: I have a small indoor heated aquarium which fits within a picture frame and hangs on the wall of my living room. The tank is about 2.5 foot long by about 18 inches high by about 2 or 3 inches deep and is fully enclosed in a wooden frame. It contains guppi

I have a small indoor heated aquarium which fits within a picture frame and hangs on the wall of my living room. The tank is about 2.5 foot long by about 18 inches high by about 2 or 3 inches deep and is fully enclosed in a wooden frame. It contains guppies and a lot of weed and snails.

A couple of weeks ago I saw what I thought was a spider drowning, thrashing/swimming in the tank. I tried to fish it out but it buried itself in the gravel and I lost it. A few hours later I was amazed to see it sitting in the weed. Upon closer examination I could see it has six legs, clearly has a head, abdomen and thorax, has a laterally flattened body and it's abdomen was pulsating, presumably to facilitate breathing. It was then about 10mm long but is now about 15. No fish seem to be disappearing and I have a number of baby guppies which are smaller than it is. But I suspect it is eating snails.

This may be a dragonfly nymph and was probably introduced on the weed, possibly as an egg. But since it is a tropical tank I have no idea whether the weed is of native or foreign origin. Obviously it would be irresponsible to release a non native insect species into the wild – although at this time of year it would probably mean instant death even if it is native.

Do you all think this is a dragonfly? More difficult can anybody tell me if this is native to the UK?

Thanks