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rain- 12-29-2006 11:34 PM

What's that bug? How to recognize them
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.


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.

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.


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.


Text coming later

Color Me Blue 12-30-2006 05:48 PM

Wonderful pics! Very helpful in identifying those lil critters.

I vote to make this a sticky too! :)

Wasserpest 12-30-2006 07:23 PM

These are awesome photos rain, thanks for sharing. I love taking macros, but this is almost micro! How did you get those springtails that big?

I'd like to make it a sticky so we can refer to it when poster #74 asks what those coral looking algae are, but I am not sure in what section either? :icon_ques

Spypet - let's omit the food worms please.

rain- 12-30-2006 07:38 PM

Color Me Blue: Thank you. :)

spypet: I don't have any experience with other creatures so I don't think it would be fair for me to present them. But if you do and have pictures and experience of those, go ahead and add to the list with descriptions, that's why this is a discussion forum, everyone can share their knowledge. :)

I challenge you to add your share to this thread. And it applies to everyone else too. If something is missing, add it. I live in cold, cold Finland with not as much exotic creatures as you guys have there. :)

I can add mosquito larvae to the list since I do have pictures of those. I've never had dragonfly larvae. Daphnia all look alike so they are good enough to be presented as one. Plant worms? Food worms? What are they? Brine shrimp are food, so they don't belong to this list, but I think that why you added it between the ().

Wasserpest: Thanks. :) I took the springtail picture with my Canon EOS 350D and 60mm macro lens. Others are mostly taken with my P&S with close-up lens. :)

epicfish 12-30-2006 09:03 PM

Wow...great thread, great pictures!

Now, how about some information about leeches? I think I either have a leech (or many) or planaria in my tank, but I can't take pictures right now because someone else is taking care of the tank.

If I manage to snap some shots, I'll post them up here!

spypet 12-30-2006 09:17 PM

rain, here's my own picture of 2mm plant worms.
most get these when their gravel gets too filthy.
fish don't seem to eat them, so you need to do
water changes and gravel vacuums to remove
and keep their population more unnoticeable.

here is an underwater picture of ianmason's dragonfly larva/pupa.
they probably come from aquatic plants grown outdoors.
you can manually remove or hope the fish will eat them.

rain- thanks again for inspiring this thread.
feel free to use this stuff in your main post.

Color Me Blue 12-30-2006 09:52 PM

Exactly! Nice contribution. That's what TPT is all about! :)

sorab 12-31-2006 01:26 AM

excellent, I was staring at a seed shrimp in the shrimp tank wondering what it was, well now I know thank you

NeonShrimp 12-31-2006 01:49 AM

I also vote to make this a sticky! And if it isn't here you can always add the pictures to the list:icon_wink

Wasserpest 12-31-2006 02:16 AM

Okay, okay, made it a sticky :icon_wink

I used to feed mosquito larvae to my fishies, and often the black ones would manage to hatch (the high temps accelerate that) and at night they would drive my crazy.

I love feeding the white ones ("glassworms"), they mady my fish go nutz, always manage to roll away when they are almost in their mouth.

350D... I am about to jump the gun and get one, either a 400D (XTI) or a 30D, which fits my large hands much better (and hits the pocket a bit harder).

Storm_Rider 12-31-2006 08:39 PM

Are those really what tubifex worms look like? There's lots of controversy and debate behind their usefulness as a food and their simularity to a blackworm. I grow blackworms at home in a container to feed to my turtles and corys but the lfs I buy them from (when I'm running low or or kill my coulture because I'm lazy and cleaning their water is hard) sells them as bloodworms.. which they obviously are not, so when I ask the manager about it, he says everyone calls them bloodworms but they're actually tubifex worms.. also which I do not agree because my research has lead me to believe they are california blackworms. The worms I have look simular to your pic but they are darker brown except when they split and form a baby, then they are pinkish for a while. They also get like 4 inches long frequently but split soon after. So anyways, I'm against using live tubifex worms unless the conditions they were raised is sanitary. Freezedried tubifex worms in the cube form are great though, press it against the glass and it's quite a show to watch if you have some sharks or aggressive fish.

rain- 12-31-2006 09:29 PM

Storm_Rider: Well, they are worms from my tank and they look like Tubifex and act like Tubifex, so I would say that they are Tubifex worms. :) Here's more pictures: tubifex - Google Image Search

California blackworms (Lumbriculus variegatus) do look a bit like Tubifex (Tubifex tubifex), but they are totally different species. They both belong to class Oligochaeta, but tubifex worms belong to order Clitellata and family Tubificidae, blackworms belong to order Lumbriculida and family Lumbriculidae.

Wasserpest: Thank you for making this sticky. I am really happy with this 350D, it fits my tiny hands perfectly. :)

spypet: Thank you for your contribution, the pictures are great. I'll be adding some information and the pictures to the first post as soon as I have time, so we will have everything in the first post and in some sort of order. :)

James From Cali 12-31-2006 09:35 PM

These stickies are great. It really can help newbies, actually help anyone, that have "bugs" in their tanks!

A Hill 01-05-2007 12:32 AM

rain- ,

Another excellent job!

I'll try and get some info on some others you missed, I get some nasty critters on the moss I collect larva of dragonflies, damselflies, small leaches, and random other things... There are some COOL damselfly larva though!

Ohh and those little coral type things, look awesome! Any Idea where I might be able to obtain some from?

- Andrew

h20 plant 01-18-2007 07:16 PM

I have a couple of these but the worst one to get rid of is planaria but not so destructive. The one that killed several of my Crystal bee's was the dragonfly larva. If you have an open top tank keep a eye out they are very ferocious and eat anything that comes close enough.

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