Little Black Bugs

[lwhite281]

I just noticed these little black bugs at the bottom of my beta's fish tank this morning. They weren't there on Friday. I didn't work yesterday so these little things appeared sometime within the last 3 days.
Does anyone have any idea what they are and if they are harmful? What should I do to get rid of them? The tank is a 2.5 gallon tank, has one live plant in it that is looking pretty thin and one male betta. I haven't added anything to the tank since I first set it up. There's no air pump or filter either. Just a heater. The picture doesn't do it justice, but those little black dots are actually bugs. They are moving or running along the bottom. I occassionaly see one try and climb up the side of the tank wall, but it falls right back down.
I would be so grateful if someone can help me figure out what these are and what I should do about it.
Thanks!!

 

[theotheragentm]

I would guess they are some sort of water flea, most likely harmless. They could have hitched a ride with something newly added to your tank. They should disappear if food source is low. Make sure you're not overfeeding.

 

[Zagz]

They could be water fleas, hard to say. I am sure they are harmless. Do a water change and perhaps feed a bit less and they should go away. I get small bugs on the glass of my tanks throughout warmer summer temps, they don't harm the fish at all.