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What's that bug? How to recognize them

267K views 373 replies 173 participants last post by  Arty and Noodle 
#1 · (Edited)
I don't know if this belongs under "Shrimp" or "General Planted Tank Discussion", the questions about tiny aquatic creatures might usually be posted in the latter one, but I've always used to put shrimp, other invertebrates, bugs and weird things under same classification.

Here's some of the most common tiny creatures found from the aquariums.

Copepods, Cyclops



Size: 0,1 - 0,2 cm, 0.04 - 0.1 inches

Copepods are small and funny looking one eyed crustaceans. They usually move around the tank glass and other surfaces, usually with one short leap at a time. Harmless, cute, there's lots of different coloured species.

Water Fleas, Daphnia



Size: 0,1 - 0,5 cm, 0.04 - 1/4 inches

Water fleas are usually used as fish food. They are tiny crustaceans and are easily recognized of their jerky vertical "swimming". They are completely harmless and really interesting creatures. I call them fat, sad reindeers (well, they look like it :D).


Seed Shrimp, Ostracoda



Size: 0,1 - 0,2 cm, 0.04 - 0.1 inches

Seed shrimp are tiny seed shaped crustaceans. They are usually a bit bigger than Copepods. They move in a same fashion as Copepods, eating all kinds of nice things from the glass/plant/etc. surfaces and you can see them walking inside the substrate too. Sometimes they swim in open water looking like drunken bees. Here's a really young CRS baby looking at a seed shrimp. Really cute, harmless.

Freshwater Limpet - Acroloxus lacustris




Size: 0,1 - 0,8 cm ; 0.04 - 0.3 inches

Since freshwater limpets, Acroloxus lacustris, are so small and also move really slowly, it might be hard to identify them as snails. They are small and can't do much damage to plants, but since they are small, it's impossible to find and remove eggs and the baby snails. Harmless.

Something that looks a bit similar are Nerite eggs. They are singular, white, hard, round or oval shaped and about 1 - 2 mm in diameter.

Tubifex



Size: 2 - 5 cm, 3/4 - 2 inches

Red, yummy worms (used as fish food too) which live inside the substrate. If disturbed and dig up, they will form a ball, if left alone, they will gather pieces of sand/gravel around their body forming a sort of tube where they live in and they'll stick their head out of the substrate looking like red hairgrass. If there's lots of them, the substrate is too dirty and might be good idea to do something about it. Only a few Tubifex in the substrate isn't anything to worry about though. They are harmless.

Nematodes
Size: 0,1 - 0,3 cm, max. 0.1 inches

Nematodes are small, thin, white/transparent free-living roundworms and the "swim" moving themselves in a wave like pattern (well, forming an S shape). If disturbed, they will swim around wriggling briskly. You can find them from the substrate and they are the ones that might appear from the filter when you turn it on. These ones are harmless, but as with any other "pest", if there's too many of them, you are either overfeeding or just not keeping the tank clean enough of debris, decaying plant matter.

Planaria, flatworms



Size: 0,3 - 1 cm, 0.1 - 3/8 inches

Non-parasitic flatworms. Crossed-eyed grossness, just pure yucky! The only small creature I dislike (I get shivers down my spine even thinking about them). If you split it, it will regenerate and you will end up having 2 planaria. There seems to be several different colours in the common ones found in aquariums, transparent, white, brown and red. There's actually nothing really horrible about them, but they can bother small shrimp and snails and might eat fish/snail eggs.

They love shrimp pellets, pieces of meat, dead fish/shrimp and they will also eat small live creatures if they can catch them. They move on the surfaces, even under the water surface and are most active by night. If disturbed, they will retract themselves (shorter and wider), let go and drop down to the bottom.

Hydra



Size: 0,3 - 1,5 cm, 0.1 - 1/2 inches

Hydra are beautiful, but a wee bit annoying creatures. They spend their life attached to surfaces (plants, glass, filter, decoration), they can move a bit, but usually don't have the need to do that. If disturbed, they will retract their tentacles and body to small buds. They catch small creatures (copepods, Daphnia etc.) with their tentacles which can sting, making it easier for them to haul the pray in to their mouth opening. They pose no threat to adult fish, shrimp or snails (might cause some irritation if they touch the Hydra), but newborn fish and shrimp fry are in danger.

The species in the picture is Hydra viridissima and the green color comes from algae living inside the hydra.

Bryozoa, moss animals



Size: individual creatures are only a few millimetres long, the colony can be tens of centimetres long

Bryozoans are interesting colonial creatures. They look a bit like corals with the hard skeleton structure of the colony. The individual creatures, zooids, are inside their own small part of the colony and they eat small particles (phytoplankton, zooplankton) floating in the water by guiding them (and water) towards their mouth opening with the fan like tentacles. If disturbed, the zooids will retract their tentacles inside the colony walls. They are harmless and really interesting.

Springtails, Collembola



Size: 0,1 - 0,3 cm, 0.04 - 0.1 inches

Springtails are cool hexapods. They are used as live food for fish that eat from the surface, for example small Betta species and labyrinth fishes. You can find them more often from soil or leaf litter than from the water surface, but once in a while they will appear on the floating aquarium plants. If disturbed, they will spring to safety releasing their "spring" (furcula) that's normally bent under their body. They can jump surprisingly far (several centimeters). Harmless and cute.

Mosquito larvae




Text coming later.

Bloodworms



Text coming later
 
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#353 ·
Any Ideas what this bug is...?

I've been finding these small bugs in the buttom of my bucket after hoovering the gravel on my tropical fish tank, their really small so I've never been able to identify them before and found this thread a while back and just presumed they where copepods or daphnia, seed shrimp etc.... and didn't really worry but have just got a small microscope and managed to get a photo, it doesn't really look like anything I've seen in this post to me, I would appreciate any advice on what they are and how I get rid of them if I can...?

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#356 ·
Are these nemotodes? I just set up a brand new 5 gallon tank with new aqua soil, new filter and new heater. I've put a few plants in there and have been letting the tank run without any fish or shrimp in it. After a few days though I noticed these worms wriggling around in the water, I've caught at least 20 of them by now. I'm almost positive they came from the plants, and I've contacted the seller/website where I bought the plants but they claim all their plants are worm-free... =( I thought these worms were only supposed to appear if there was an excess amount of food left in the substrate?

http://youtu.be/g1J45R1pgG8
 
#368 ·
I found this ugly guy a little bit ago and I've gleaned from this thread that it is a snail leech and it probably won't bother fish (likely deadly to snails).

I can second this observation found over on this thread on another site:
When taking them out of the tank they feel pretty hard. If you don't get a good grip on them right away they curl up.
This one dies today, but I'm not sure if I have to go hunting for any more that might be in my tank. Are they harmless?



 
#371 ·
I just image googled "snail leech" and ran across quite a few pics that looks like that one up above.

Also, the pic above looks like there is segmentation, which is a pretty big characteristic of annelids compared to other worms.

It is rather odd looking, with whatever internal systems giving it that strange marking pattern thingy.
 
#373 ·






https://imgur.com/0lnvuM2
https://imgur.com/n1fBNwd
https://imgur.com/Db9QmrW
https://imgur.com/9RuQoAT
https://imgur.com/9RuQoAT
Are these Ostracod or something else? (The dark lines at the background in the photos are the one millimeter marks of a ruler.)
Ever since these bugs (multiplied to the thousands) invaded one of my shrimp tanks, they've nearly wiped out the existing copepods population that is essential to the growth of the nano fish baby fry. I also noticed there are less baby shrimps survived into juveniles after hatches.
Is there any effective way to eliminate these bugs without breaking down the whole tank?
 
#374 ·
It seems this page hasn’t been used in a bit but I really hope someone answers me soon incase my aquarium situation becomes urgent. Hi, I just started my first planted tank with hornwort and Java fern. After adding the hornwort which I bought off Amazon, I saw these small bugs that look identical to the hornwort needles. I immediately threw out the hornwort after discovering other horrifying things. I’ve done three water changes and vacuumed the gravel maybe five times since hoping the bugs would be removed. I believe I’ve removed the majority but I’m still worried they could harm my fish when I add them.what arethey i’ve added a pic.
Hood Grey Wood Asphalt Slope
 
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