Problems with white fungus?

[pagemee]

I have small involvement with my boyfriends tank I made him get because I don't get to see it everyday, but the betta in the 10 gallon was sluggish two days ago and then I saw him the next day and he had a mane of white cottony substance that just incircled his head and gill area. The white stuff is also growing on the filter cord and some plant leaves. I'm treating the tank with API fungus cure yesterday but the betta died today. There are also four neons and a ghost shrimp who are all normal. I tried researching if the medicine would hurt Waldo the ghost shrimp but nothing he's also still alive. I've been googling it and can't find anything that says it grows on fish and plants and plastic objects. I'm confused. No pictures of it sorry, maybe I'll take them tomorrow when I dose the tank the second and last time if I still see any.

[Aeonflame]

Fungus is usually the result of poor water conditions and stress. How often do you perform water changes? What are your parameters? Is the tank heated?

[pagemee]

Water conditions are all in range. It's heated. It might have not finished cycling yet but I'm looking for a more specific answer as to what type of fungus can grow on plants, fish and plastic things.

[CherrySparkles]

White or greyish, cottony looking growths, are often called fungus, but this is a misnomer - in all likelihood, it is a bacterial infection called Columnaris. I think this is especially likely in your case as it can have a typical "saddle" like presentation on a fish. This is a gram negative bacteria that responds well to treatment with the antibiotic kanamycin sulfate (found in Seachem Kanaplex). I personally have treated with this and had great success.

Real fungal infections are much less common in the aquarium than bacterial, and it can be a fine distinction to make. Fungi tend to appear more fluffy, while columnaris is more slimy looking and flat, with some "wooliness" in appearance, in my experience.

Here is a good article on columnaris in bettas:
http://nippyfish.net/sick-betta/cott...-disease-flex/

And here is an excellent, though lengthy, article on distinguishing columnaris from a real fungal infection. It's well worth your time to read it and hopefully will give you a great understanding of what you're dealing with. This article also suggests alternate treatments if you're not able to find kanamycin (my personal favourite):
http://www.americanaquariumproducts.com/Columnaris.html