What exactly is fungus? I've never been clear on what it is.

[FINWIN]

Is it flagellate, microorganism, bacteria or plant based related to mold? I've seen it on fish in large tufts with strings, clumps like cottage cheese or clusters of little balls. I'm just trying to understand better what makes it suddenly appear and flourish without warning and what is most effective against it consistently.

 

[Azedenkae]

Fungus is a eukaryotic (multicellular) kingdom of organisms, like plants or animals: https://en.wikipedia.org/wiki/Fungus.

It is not a flagellate. Some of them can be microorganisms (defined simply as very small organisms). Not bacteria, nor really closely related to plants either. Mold is a type of fungus. Mushrooms too.

Broadly they are very good detrivores and subsists on all manners of substrates, so different types live in very varied environments.

 

[Redshark1]

Fungi cannot make their own food like plants do through photosynthesis.

So, they gain energy and nutrients by breaking down organic material from other living organisms.

This is usually material that was once alive but is now dead but some fungi can feed on living material too.

Fungi usually reproduce by producing spores which are like tiny seeds that need magnifying x400 to be visible to the human eye.

Spores are present in the environment on the land, in water and in the air and just need to land somewhere suitable in order to germinate and grow into a new fungus.

 

[duanes]

Many aquarists mistake certain bacterial diseases for fungi, because to the naked eye, many diseases produce similar. looking symptoms.
And mistreat.
Only under the microscope are many true differences discernible.
Coloumnaris is one of those often mis diagnosed as fungi, because it sometimes produces white tuft like columns that look like fungus but aren't, and the misdiagnosis lead to the use generic anti-fungal meds that don't do the job.
Columnaris requires a gram negative antibiotic instead.

 

[FINWIN]

So then without a swab or tissue samples its trial and error with meds (bacterial/fungal)?

 

[duanes]

So then without a swab or tissue samples its trial and error with meds (bacterial/fungal)?

This is true.
Proscribing meds for fish without really knowing what the source of the problem is, is at best a shot in the dark, that could do more harm than good.
I have even seen cases of Lymphocystis being called a "fungus" by well meaning aquararists, when it is really an irido-virus,
and there really aren't any medications available to cure it at all.
Almost all medications are toxic compounds that in small doses, will kill properly identified parasites or bacteria, but hopefully don't kill the host.
The problem comes in when, (because of the immunocompromised condition of the fish) the toxicity reaches beyond its intended target, or worse, when the overused medical toxin has no value at all.
PreviewPreview11:09Fungus under Microscope Fungal structures AspergillusYouTube · Microhub Plus11 minutes, 9 secondsOct 27, 2019