I'm no expert by any means but I think with good filtration and water changes, you should be able to squeak by with those fish. I have a 55gallon with an overstock of danio's, tetras and livebearers and use a penguin 330 along with a bio-wheel 60 Pro and do weekly 25% waterchanges. At first I was overfeeding and my nitrates spiked so I did a large waterchange and stopped feeding for 5 days. After that I changed my feeding habits and have not had a week over 10ppm nitrate since and never see nitrite or ammonia. My fish are very happy and don't seem crowded at all. On the otherhand, the danio's are a little more active than most fish and I think they would be happier with the added length of a 20 or 30g tank. If you had more tetras and less danio's, I'd say go for it. Kyle