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ok i started with a small school of neons, i lossed several when i moved. i unfortunetly only have 2 left. i went on vacation this passed weekend and when i came back home i noticed one had plumped up a bit... what could this be from?

*click *flash *click "whered he go???"

There's a chance it's bacterial dropsy. In that case, I'm afraid you're going to lose that particular Neon -- dropsy seems to be almost impossible to treat once it becomes visible. You might try antibiotics, but I doubt it'll be worth your while.

The best way to avoid losing future fish to it is to keep your tank as clean as possible -- and that includes putting a couple of catfish or loaches in it to eat all the food after it hits the bottom and before it starts to decay. I've found out, the hard way, that fish tend to eat half-decayed food off the bottom otherwise and give themselves bacterial food poisoning (dropsy being one form of this), and that this in fact seems to be the disease that kills the most fish. So keeping an adequate staff of bottom-feeders is as important for your fishes' well-being as is having a working filter system and also changing about 10% of the water in the tank per week (to remove the poisons that the filter system won't remove).

A few additional questions: how big is your tank, how many fish were you trying to keep in it, and did you "cycle" it with a few tougher fish before putting in the Neons?

this tank has been up for about 7 months so it is cycled i havent had a problem with any of the fish other than the neons lost during my move to a new house.i cleaned the tank the day before i left soe im kinda nervous as to what it was. i noticed that something similar happened to my zebra danio

*click *flash *click "whered he go???"

ive had a few experiences similar to this with the problematic neon tetra, so i switched to the slighty more expensive cardinal tetra and have kept my school of 4, for about 5 months now.

it hasnt seemed to be a problem yet. he is still active, and hasnt changed any behaviors. hes just a bit more plump then the others

*click *flash *click "whered he go???"

Could be that he's just the dominant fish in your school and therefore has the most food. Maybe you're feeding too much?

There is another possibility.

Your "plump" Neon Tetra could be female.

First of all, to rule out disease, look at the fish from above. If dropsy is an issue, then the fish's scales will stand out from the body at an angle, and this is most prominently seen from directly above the fish over a dark background. Once the scales are standing out at an angle, then your fish is a terminal case I'm afraid - dropsy is a symptom of a more serious malaise involving liver failure (which may or may not be brought about by bacterial infection as per Bruce's notes above) and this manifests itself in increased fluid retention (the kidneys are usually starting to go AWOL at this stage also, because the failure of the liver results in compounds toxic to the kidneys building up in the bloodstream instead of being metabolised). The increased fluid retention causes the scales to stand out at an angle.

If dropsy isn't an issue, the next thing to check is feeding. If the fish appears plump after mealtimes, but slims down a bit after a few hours, then you're just seeing a normal, healthy fish enjoying its chow.

If the fish retains plumpness outside of mealtimes, but is otherwise healthy, then chances are your fish could be a female, and becoming ripe with eggs. I've noticed that some of my Cardinals are noticeably plumper in outline on a permanent basis, and furthermore that one or two of the plump ones are chased on a fairly regular basis by slender individuals in the shoal. This is usually a prelude to spawning. However, it has to be said that persuading Neons to spawn is quite a challenge, and breeding the species (i.e., producing a nice batch of fry that grow up to be fully fledged juvenile fishes) is a task that veteran aquarists consider to be a test of their skills, because Neons have intricate breeding requirements!

So, if you suspect you have a female looking for a male to spawn with, my advice is to acquire some more Neons to give her a choice of partners (acclimatising the new ones with particular care since your local specimens appear to be delicate) and once you have a shoal, then it's time to set about constructing your breeding aquarium. This is where it starts to become a major logistical exercise.

While Neons will breed in a modest sized aquarium, there are certain requirements that MUST be fulfilled if they are to breed. First of these is soft, acidic water, ideally filtered over peat and containing humic acids, resembling their native waters. If your fishes are living in water that differs substantially from this chemically, then you have to spend time acclimatising your Neons to the breeding water. Logistical chore number one.

Next, having created your breeding aquarium complete with soft, acidic water and peat filtration, you then have to provide spawning mops. The reason why synthetic spawning mops will be needed becomes apparent shortly. The fishes will spawn in a natural medium such as Java Moss, but, to make life easier, a synthetic alternative is actually preferable here. This is because, wait for it ... you have to spawn the fishes in darkness.

In the wild, Neons migrate to stretches of river that are cut off from overhead daylight by rainforest canopy overgrowing the narrow stretches of stream and creek that eventually merge to form the larger rivers. It is here that the Neons breed. Over geological time, the Neons (and their relatives the Cardinal Tetras) have undergone a mutation whereby the eggs are photosensitive - they die if exposed to bright light. So, the fishes have to be spawned in an unlit, shaded aquarium, and the once the parents have spawned and have been removed from the breeding aquarium, the breeding aquarium has to be darkened - it has to be surrounded with opaque material so that the eggs are kept in TOTAL darkness for 72 hours!

Now you can see why Neons are a challenge to breed. If you want to try this with your fish, if your plump specimen is indeed a ripe female, then I encourage you to try, be be advised that this will be a MAJOR test of your fishkeeping skill, and if you DO end up with viable fry, you will have achieved something rather special.


Panda Catfish fan and keeper/breeder since Christmas 2002

Didn't I read somewhere that the sex of neons could be determined by the kink or the lank of a kink in the blue line indicating it to be either a male or a female? But I don't remember which is which?? I noticed a couple of mine have a slight kink in the blue line. The rest are straight. Does anyone know if the kinked line is a male or a female?

Now that's a diagnostic indicator I haven't seen documented anywhere before now ... I'll have to check this one out.

If this turned out to be a reliable means of sexing Neons, then my guess, prior to any investigation as to the veracity or reliability of this technique, would be as follows - a kink oriented in THIS direction:

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would indicate a female fish, due to the effect of abdominal distention in a ripe female causing the back to arch slightly in that fashion. A straight line would indicate a male. This is, of course, purely ocnjecture on my part, and relies very heavily upon the as yet unsubstantiated existence AND reliability of this sexing method.

If anyone can point me to a literature reference which cites this technique, and gives some indication as to reliability, then I'd welcome it.

However, I would then have to ask why this does not appear to be the case for Cardinal Tetras, which are after all related.

Next time I take a peek at the Neons in my LFS, I'll see if any have kinks in their colouration.



Panda Catfish fan and keeper/breeder since Christmas 2002

http://www.angelfire.com/ok5/ryan_88/characins/neontetra.html

http://fish.mongabay.com/species/Paracheirodon_innesi.html

http://groups.google.com/group/rec.aquaria.freshwater.misc/browse_thread/thread/208429df2f7703bd/cfd293272477b1dd%23cfd293272477b1dd

Interesting ... so there's more than one source that says 'look for a kink in the stripe'. Hmm, now the question is, is this criterion reliable? Because if it is, it'll make pair selection for a breeding programme a LOT easier.

Guess I'll have to watch this space.


Panda Catfish fan and keeper/breeder since Christmas 2002

Hmmmm I can't seem to edit my other post anymore, so here's another one:

http://www.theaquariumwiki.com/Neon_tetras

http://www.aquariumlife.net/profiles/characidae/neon-tetra/100034.asp

http://www.tropicalresources.net/phpBB2/fish_profiles_innesi.php

Is this enough Cali. or do you need more?

The kink was the way I was told years ago to sex neons too-and that was at least 7 or 8 years ago.

Hmm - again, I'll have to see if this pans out as a reliable means of differentiating male from female. However, one has to take into account that unreliable information has a way of propagating itself too, as any number of threads in here will testify (particularly with respect to the bad information promulgated by some dealers).

If this technique does indeed prove reliable, I'll add it to the database. Interesting that the same feature doesn't seem to be documented for Cardinals though ...


Panda Catfish fan and keeper/breeder since Christmas 2002