Why do i have orange spots on the plastic plants & decor in my freash water aquarium?

Answer 1

Sounds like brown algae.

From Robyn's site (linked below)-
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"Brown Algae
Aquariums:

Brown algae are actually diatoms and not true algae. They coat ornaments, real and fake plants, glass, and gravel with a thin, dark brown layer. Brown algae prefer low light levels. They commonly grow in new tanks or those with low levels of light. Increasing the intensity or quantity of lights may decrease the growth of brown algae but in turn will increase the growth of other algae. Brown algae is easy to physically remove with an algae pad as it does not adhere as strongly as green algae. While some snails and algae-eating fish will inadvertently eat some brown algae, most algae-eating fish prefer green algae and will only eat brown algae if they have no alternative food source. Plecostomus and otocinclus are the most likely fish to eat it.

Ponds:

Brown algae is less common in ponds because outdoors, there is plenty of sunlight, and brown algae like low light levels. It may grow in darker areas of the pond."
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I find Robyn to be the best source to learn about the different types of algae and what can be done about them. She also provides links to more info.

I doubt it is fungus, and if it is, there are medicines that will kill it. I would operate first on the presumption that it is brown algae and act accordingly. Fungus is found on the fish, not on plants and decorations. If it is a fungus, you will notice a problem with your fish eventually, but again, I know of no fungi that can't be treated.

If you empty your whole tank, you will lose your cycle.

Also, I know of no FISH-safe cleaner. If one is out there, I'd love to see it. ANIMAL safe is NOT the same thing as FISH safe.
It does not refer to animals which LIVE in and BREATHE water!!
PLEASE don't use any cleaners on or in your tank.

Answer 2

Fungus is usually white and fuzzy.

Is it an orangey coating of gunk on everything? If so that is like brown algae, which are actually diatomes and should go away when the water settles. Use your gravel vac to suck up the gunk and keep up with weekly water changes; it'll go away eventually.

Is it more like dark orange and furry? That may be red algae aka black beard algae. But it probably would not grow in a tank with no live plants. If it is BBA, it's hard to wipe off. Decrease the amount of light your tank gets, say to 8 or 9 hours of light per day, and if your tank is near a window, consider moving it or covering the side of the tank that faces the window.

Answer 3

ALGAE - Could be new fish tank cycling, or time for a 50 % water change. Too many phosphates.

Answer 4

fungi... clean the aquariun withan animal safe household cleaner... bag the fish while you do it, but use the same temp water, and get the water back to the same temp after you clean and refill the tank, if you don't the fish will die of shock.