Mostly what people consider low light plants are Anubias, ferns, mosses, and Cryptocorynes, (some, not all). Everything else is highly subjective to ones own interpretation. For example, Aponogetons and Tiger Lotus. Under proper light and conditions these plants grow to be huge. Aponogetons leaves grow to over 2 feet, and one full grown Tiger Lotus can nearly fill up a 29 gallon aquarium. I have seen some WEB sites list Cabomba and Anacharis as a low light plant, which is kinda ridiculous. A sword plant under low light might not die and stay six inches tall for a year, but under proper conditions would reach almost two feet in height and have over 30 leaves on it within six months. I would disagree with over half that list for true low light plants, but an online dealer like that doesn't really define what low light is, and many people don't even agree on what the minimum should be. I found if you have a minimum of 2 watts of flourescent light per gallon of water, you can grow most plants except the most light demanding. But I still call that low light. If you have less than that, your best bet for healthy plants is any Anubias, water ferns, aquatic mosses, and some Cryptocoryne species, (mostly the common Sri Lanka species like wendtii, lucens, lutea) Most other plants would struggle.
