Are those water beads? My son uses them. They will break down into small pieces after a while. Just something to keep in mind. Not toxic. If they are water beads.
If they are glass marbles should be ok if they are something else then, No.
My first reaction was Why? Why would you use this in an aquarium?
I can understand it, if they are marbles I guess.
I think that they are beads but i have seen this resist for 2 years and more . I dont know what this are but my friend said that have used like this in his goldfish bowl ago.
Thanks for everybodys helped .I Think that i wont put this in my aquarium becouse if they arent a problem for small fishs i think kois are enough big to eat them .