Hi folks,
As previously mentioned, I stopped using a light in my tank after the tetras developed an aversion to it and seemed traumatised any time it was switched on (
http://www.thinkfish.co.uk/forums/general-fishkeeping-advice/advice-re-change-of-lighting/msg15445/#msg15445) although they are used to the dim light of a table lamp which sits beside the tank. As the fish seemed happy and content, I've just let the situation remain like this. Consequently, I've only ever had silk plants in the aquarium as I reckoned that even Java fern would struggle to survive.
During the week, inspired possibly by the various posts of people's tanks, and wondering how much easier it would be to see the fish with the tanklight on, I decided to experiment by switching on the light again. The good news is that the fish's reaction wasn't as adverse as previously - tetras remained coloured and didn't cower/shake (Richard W's excellent suggestion of getting more fish of similar size to the tetras to make them feel safer and more confident has definitely helped generally and re this). However, both the tetras and harlequins did keep their heads hidden under the plants and, any time they came out to try swimming, they quickly shot in for cover under the plants or the wood, despite me adjusting the two taller plants to cover as much of the water surface as possible. [The pics seem to make the tank look bearer than it is - the coverage seems to be greater than this "in real life".]
Having already tried the original Sun-Glo and the less-bright Aqua-Glo light, I think the only way that it's going to be possible to have a tank light (which I'd quite like to view the fish better and possibly to be able to grow some Java fern) is if I go for something dimmer. I'm attaching here pics of the tank with the table lamp on and the Aqua-Glo light - any suggestions for something in between? [I appreciate, from the previous thread, that black substrate might help the situation too, so I'll revisit that plan which I shelved at the time.] Thanks.