Unknown creature in my 20 gallon gold fish tank

[KRAKEN]

There are about 4 of them, I am clueless of what they are, but they are eating scum off the bottom of the tank, (food, poop, ect) what are these things ?

[Lainey183]

Could this be it?

Those Little White Bugs In Your Saltwater Aquarium Profiled - Classification Information and Facts About What Eat Copepods and Amphipods

[xtra51]

Originally Posted by Lainey183

Could this be it?

Those Little White Bugs In Your Saltwater Aquarium Profiled - Classification Information and Facts About What Eat Copepods and Amphipods

This is freshwater, not saltwater.

[KRAKEN]

Fresh water....

[Starka]

The tail from what I see is earwigish? How big is it?

[LyndaB]

Looks like some kind of larvae....... reminds me of mosquito larvae, but I don't think that's quite it.

[KRAKEN]

It's smaller than my pinky nail, to me it kinda looks like a baby cray fish? I'm surprised my iPhone focused on something so small

[KRAKEN]

I picked one up and it feels like a shell, like it's hard

[Lainey183]

If you had actually read the link it says they can be in both fresh and saltwater.

Anyway, have you added any live rock recently? Or plants?

[Lainey183]

Copepods occur in all types of aquatic ecosystems; freshwater, estuarine (brackish) and marine.

Amphipodsare mostly found in marine ecosystems, but there are some freshwater and terrestrial species.

What Do Amphipods and Copepods Look Like? - Amphipod & Copepod Pictures

If you actually click the link you will see pictures, I think it looks pretty close to what you have pictured.

[KRAKEN]

I added a rock from fresh stream in back yard

[Lainey183]

That may be where the mysterious creatures came from. Are they bothering your fish?

[Lainey183]

I have been doing some research on adding drift wood to my tank, and it says you are supposed to boil it... I assume the same would be true for rocks.

[herp_mommy]

looks like Mayfly larvae. I know dragonfly larvae get big enough to eat frogs and fish. I would remove them.

[KRAKEN]

I'm going to let it play out, if they get big and I feel they are a danger I will remove them, as for right now it seems like they are doing a good thing by eating the left overs, and my shubunkin ate one, so it it's acting as a natural food source I'm fine with that,

[Wy Renegade]

Hard to say for certain from the picture, but it does indeed appear to be a mayfly larva. Unlike damselfly or dragonfly larva, mayflies are herbivores, and will not cause any issues with the fish or other invertebrates. They are also indicators of very good water quality, which makes me question that I.D. in a goldfish tank. They may be damselflies. Distinguishing between the two is easy in person. If the middle filament of the tail is held in line with the other three, and they appear to be only filaments, then you have mayflies. On the other hand, if the filaments appear feathery or gill-like (which they are), then you have damselflies. Regardless, neither type of larva is likely to get big enough to cause any issues with goldfish, so leaving them to play out should be fine.

Since the picture appears to show gills on the abdomen rather than on the tail filaments, I'm more inclined toward the mayfly larva, even though it is a goldfish tank.