Danios | Surprisingly Vicious Little Fish
Danios, both the pearl and zebra type are often sold to provide a bit of added life and movement to a tank. When you have fish that mostly swim languidly about the place, seeing these small tropical cousins to minnows dashing about the place like a CEO looking for bailout funds is quite pleasing.
Though they are small, a minimum of a 20 gallon long is recommended because they do love to swim frantically about the place, and smaller tanks just don't give them the room to really get their fins moving. If you have a smaller tank and want some pretty little fish for it, try neon tetras or cardinal neons, they're both lovely little fish that do not require nearly as much space as your average danio.
The other thing you should be aware of when keeping danios is that they are best kept in groups of 6 or more. They love to school and swim about with one another, and may become quite stressed if they are unable to do so due to insufficient numbers.
However the title of this piece referred to the vicious nature of danios, didn't it? In what way are they vicious? Well, for little fish, they are incredibly voracious. Small fry do not stand a chance in with danios, even if you think that the fry are probably too big for the danio to eat, a swarm of them can attack a small young fish and tear it apart in seconds with all the aplomb of a pack of pirahnas.
They are enthusiastic eaters of non live food as well, and like most fish, soon learn to hang about near the front of the tank at feeding time and will pounce on food the moment it hits the ground. Schooling behavior as they eat can also be observed, as they wiggle into the mix, grab some food, then swim out again before circling back for more.
Truly, danios are some of the most underrated little tropical fish on the market. Zebra danios are my personal favorite because of their interesting finnage, which, when viewed from above looks quite bat-like and the blue stripes that give them their name.
If you have a tank with small to mid size fish and are looking for some interesting dither fish, I could not recommend danios highly enough. These hardy, boisterous fish will demand your attention and provide hours of amusement.