My aquarium (180 l) is inhabited by two Mikrogeophagus ramirezi, several Corydoras julii and some uninvited ranshorn snails.
Today three of these structures appeared. They are white, around 1 cm wide and between 1 and 3 cm long, very thin, and look foamy. They appeared rather quickly, I do not think they where there yesterday.
Can somebody identify what this is? Are these eggs, or something that I should be worried about?
I can exclude eggs from the ramshorn snails. I had those before, and they look completely different. But I never had fish eggs before, and I cannot find images of something looking like this.