FishProfiles.com Message Forums

We noticed this in the tank this morning, swimming towards the top of the water. When we fished it out and put it on a napkin, it stopped moving. What is it??

http://i84.photobucket.com/albums/k16/PanClan06/IMG_1076.jpg

Our tank: 45 gallons
7x Cardinal Tetras 7x Black Neon Tetras
7x Glowlight Tetras 2x Ottos 2x Ghost Shrimp 3x Spotted Corys 3x Panda Corys

I am inclined to say that it's an insect larvae, which would account for its sudden cessation after you removed it from the water.

I would guess it's a dipteran, but I'm not positive about that.

That looks like something I'd send to a university extension office. They handle this kind of thing all the time (I know some profs in extension here).

><>

It appears to be a dragonfly larvae or a relative. It may have come into your tank via eggs on plants or stones. Dragonfly larvae are predatory and will take fry and small fish.



__________
"To steal ideas from one person is plagiarism; to steal from many is research."
researched from Steven Wright

Are the fish in danger?? We have tetras and an algae eater (whom I would think is too big for the larvae).

Our plants are fake, not sure if eggs could have been carried on them.

We clean the tank every week, change the water. I'm thinking we should clean out the tank thoroughly tonight or tomorrow night and make sure everything is spotless. I read somewhere about boiling the gravel... would this be necessary??

Our tank: 45 gallons
7x Cardinal Tetras 7x Black Neon Tetras
7x Glowlight Tetras 2x Ottos 2x Ghost Shrimp 3x Spotted Corys 3x Panda Corys

Without a proper look at the critter, it's difficult to say what it is. Any chance it's still alive? Put it in a jar and photograph it there. Only it's a LOT easier to determine the nature of aquatic insect larvae when they're alive

No need to strip the tank. For one thing, the chances are this creature made its entry with some live food administered to the fishes - that's the usual route by which such interlopers turn up in aquaria. There are those among us (people like me with an interest in entomology) who keep such creatures for their own sake, but we're in a minority.

Remember, many insect larvae are actually fish food. Bloodworms are a prime example. Mosquito larvae and Glassworms being two others. There are some larvae that could be dangerous to small aquarium fish (the larger dragonfly larvae, larvae of big water beetles such as Dytiscus) but these usually make their present manifest in live food a good way before they reach a size that could be of danger to your fishes, and are easily weeded out. That is, of course, if you do the sensible thing with live food, which is to rinse it in a net and check it for interlopers before feeding it to the fishes. Some people don't do this, they just open the bag and dump it in, which is, er, not recommended for a host of reasons.

Worst thing you could do is tear the tank apart unnecessarily. Do that and you're looking at rebuilding your biofilter unless the operation is performed with great care, and as a consequence, you'd be subjecting your fishes to the stresses of cycling all over again. This should be a 'last resort' operation brought about by dire necessity because some catastrophe has been unleashed that won't go away without such drastic measures, and the appearance of one odd critter of this kind in your aquarium does not fall into that category, you'll be glad to hear.

Prevention, however, is better than cure. So, if you're feeding live foods, screen them before feeding them to your fishes. Check for extraneous critters and remove them before feeding the live food, and all should be well.

Oh, by the way, some extraneous critters are actually desirable. I found Crangonyx pseudogracilis in one batch of Daphnia I fed to my Panda Corys - and I'm looking for more, because these things are small freshwater amphipods that make great fish food. If I can lay my hands on those critters and cultivate them at home, I'll be very happy.


Panda Catfish fan and keeper/breeder since Christmas 2002

Thank you Cali... we actually don't feed our fish live food. We give them tetra flakes, once in a while dried bloodworms as a treat, and Herbie gets algae wafers.

The larvae is in the trash, probably smushed by now. If we see another one we'll try putting it in a container of water and maybe bring it to our LFS. Hopefully they can tell us what it is and give us suggestions.

For now we'll leave the tank alone, we'll keep an eye on things.

When my son was feeding the fish this morning it seemed the larvae appeared from the top of the tank. Checked under the hood, didn't see anything suspicious. Checked the food, it seems okay.

I thought about the fish eating it, but since I don't know what it is I'd rather they didn't have it as a meal. The fish seem fine, none of them appear to be sick, but I will continue keeping a watchful eye out.

Our tank: 45 gallons
7x Cardinal Tetras 7x Black Neon Tetras
7x Glowlight Tetras 2x Ottos 2x Ghost Shrimp 3x Spotted Corys 3x Panda Corys

Here's a picture of a dragonfly larva:
http://www.caudata.org/cc/images/articles/raising/dragonfly1JOHNSON.jpg
I wouldn't worry about your fishes.

As for the origin, it may simply be that an insect landed near the water and dropped eggs into it, with one surviving the tetras. I dealt with this one summer (I don't know the insect name, though). I saw a fly on the side of the tank above the water line (the water was not filled to the top) and days later there were larvae squirming around the side. I forced them into the water, and the fishes enjoyed the live meals and I got to save some of the flake food.

I once had a stonefly larva slip past my beady eye in a live food shipment. Stoneflies have larvae that look like dragonfly larvae but for a couple of subtle differences at the abdominal end ...but their diet is completely different. Stonefly larvae are algal grazers.

I also has a larva that didn't escape my attention when I saw it in one of my Daphnia bags ... and I photographed it. It's since been identified as a water beetle larva, called Acilius sulcatus. This creature is seriously predatory, and if I hadn't removed it from the Daphnia bag, and it had made its way into the aquarium, it would have wreaked havoc ... Photo follows!


Attached Image:

Acilius sulcatus larva

Panda Catfish fan and keeper/breeder since Christmas 2002

Wow... seems like this is a common situation!!

So I guess we don't have to worry... you know, the last time we changed the water I thought I saw something on the edge of the bucket that looked similar to what we found the other day, but it was smaller & whitish in color, as if it had dried up. At the time I shrugged it off as some type of debris, especially since the fish all seemed healthy. They still do.

I just wish I knew where the larvae came from... I guess eggs could have gotten in there from an insect, but we have hood on the tank. Anything is possible, I suppose.

For all I know the fishies are finding the larvae before we are, and having midnight snacks without our knowledge!!

Our tank: 45 gallons
7x Cardinal Tetras 7x Black Neon Tetras
7x Glowlight Tetras 2x Ottos 2x Ghost Shrimp 3x Spotted Corys 3x Panda Corys

Well in my case, feeding live foods to my fishes brings me into contact with all kinds of strange and wonderful aquatic life forms ... ranging from the larva whose photo I included above, to the highly desirable Crangonyx pseudogracilis freshwater amphipods that I want to obtain in numbers so that I can breed them as fish food because they make excellent snacks for all kinds of fishes

Here is a picture of the creature in question - Crangonyx pseudograciis, a native of North America and a creature that has been introduced into British waters (whether by acccident or design is unknown) and which appaently makes excellent food for young Salmon and Trout.

Here is another picture of the creature.

If anyone finds this freshwater Amphipod in local waters, it's well worth cultivating. Not only because it makes fine fish food, but because it eats blanket weed. So it's a good creature to have residing in a pond.

Basically, to cultivate this creature, you need a small aquarium (a 5 gallon one will be more than ample), equipped with aeration, ideally some form of biological filtration such as a sponge filter or an airstone driven undergravel filter, some plant life to wander among and hide, and algae to graze upon. It will also feed upon small amounts of vegetable based fish food.

However, a word of warning is apposite here - I just found this document in which scientists at Leeds University in the UK found a new species of microsporidian living inside these amphipods. The organism in question, Fibrillanosema crangonyctidae, is transmitted from amphipod to amphipod via the ovaries, so for the moment it is assumed that it is a coeval of the Crangonyx amphipod that parasitises the amphipod exclusively. As the microsporidian in question is entirely new to science, and thus little is known of its liekly propensity to jump species, one should exercise some caution with respect to the organism in case it proves to be a pathogen of aquarium fishes. Thus far, no such reports have been received, presumably because no-one has experimented on a large scale with Crangonyx cultivation as an aqwuarium food item. This new information will of course be taken into account when I begin my own Crangonyx cultivation experiments, though I suspect that the organism may be specific to the amphipod. Anyone who is interested in using Crangonyx as a fish food item, however, should bear this new discovery in mind, even though no signs of transmission to fishes that eat Crangonyx in the wild, such as Salmon and various Trout species, has yet been reported.



Panda Catfish fan and keeper/breeder since Christmas 2002