Glofish Tetra Illness


Hello! I just set up a 30-gallon uniquarium less than two weeks ago and almost immediately got some new glofish tetras.
Unfortunately, due to a whole slew of circumstances (mainly I needed to take these fish from a man that was getting ready to toss them out because he wanted a new parrot fish), I was unable to employ the fishless cycling method, so it's been happening fish-in.
I brought back some of the water that the person I got the fish from had in his tank in hopes this would help ease the transition a little (he had no gravel in his tank or media he could supply me).

There are a total of 12 glofish tetras and one leopard cory. The two green tetras are the smallest and skinniest of the bunch, and I'm not sure if they're just smaller in general or if they're younger than the others which are easily more than 2x larger and fatter than the green ones.
From day 1, the two green ones have acted a little strangely, one moreso than the other one. Even before I put them in the 30-gallon tank, they were the two odd men out, but they started off somewhat normally.
I've been doing regular water changes every other day 20-25% each time. I do vacuum the gravel a bit to get rid of any excess waste, but mostly I leave it alone so as to not remove too much beneficial bacteria until the tank finishes cycling.
Oddly enough, it seems like every time I change the water, that's when those two act the worst, swimming at the top and just kind of hovering in place for hours, but by the next morning, they're "fine" again and acting normal.
I haven't had any major spikes of ammonia, nitrite, or nitrates, but there are some levels as to be expected. Currently, I'm at 0 ammonia, .25ppm nitrite, and 5 nitrate. PH level is 8.2 and temp is 78. I've only fed them four times since Oct. 1 when I got them, and I give them only a pinch of food so as to not cause any severe ammonia spikes while still making sure they all eat.
I've since gotten three aquarium plants in hopes it would help the cycle move along a little better, and I use Prime to condition my water. I've also added a little extra Prime a couple of times to help neutralize the nitrites and nitrates.
Both green fish swim a little oddly and always have, but one seems generally in better spirits than the other and seems to swim around the tank just fine. Both sometimes will hover towards the top, corner of the tank (not gasping for air, just hovering).
The healthier one occasionally chases some of the larger fish around a bit, so it seems he's got more energy and willingness to be part of the school.
The one in worse shape swims fine one moment, and then the next, he's swimming at odd angles, or sometimes even lying sideways for a moment or head down in the plants or against the tank. He kind of hovers in place and doesn't really move, or if he does, he just moves enough to right himself and then seems normal again. He generally stays away from the school, but once in a while he has been known to swim with the group.
Both of them seem to have a little bit of a "crook" in their spine, but nothing too overt (I honestly can't tell if it's a true crook or if they're just so skinny their spines are slightly more prominent). It's mostly noticeable when they swish their tails from side to side, not so much when they're just in place.
Yesterday, the current of the filter was knocking the one in bad shape around, and he was just drifting with the flow of the water and getting spun around, so I used my old fry enclosure to separate him within the same tank. The uniquarI'm has some slits for water to flow to the back area where the filters are located, so on a few occasions, both of the green fish have gotten sucked into the slits (one even got stuck in between the slits for a bit before I was able to push him back into the tank, but he's been ok ever since).
I figured putting him in the fry net would help not only with keeping him separate from the other fish since some were starting to mess with him, but it would also prevent any possibility of him getting sucked through the slits again (the others are too large to fit through). I also thought it would keep him in a more low water flow area of the tank so he doesn't struggle so much and would keep him in a smaller space so he wouldn't have to swim too far around or compete with the others for food.
The other green fish would not leave his side once I put his buddy in the fry enclosure, so I put him in there as well so they'd have some company. After I did that, both fish seemed noticeably more relaxed and swimming normally.

Today, unfortunately, the one with the bigger problems is starting to swim extra funny. He will lie down at the bottom of the net on his side, or even "recline" against the side not really moving for a while before he starts to swim around again. He's starting to swim at even more of an angle at times with his head completely down in a vertical position at times, or other times his body curls while he's floating on his side. He only does it for a short bit, but it's happening more regularly. Other times, he starts to swim around completely normally as if nothing is wrong.
It's frustrating because one moment it looks like he's about to go, and the next he seems totally fine. I fed them a bit today, and they both ate with no problems.

My issue is, I can't tell if he's behaving this way due to illness, stress, or he's just born with an abnormality of some kind and will eventually be fine. I can't tell if he's dying or sick with a disease or just swimming funny because that's his "natural" state on account of some birth defect. The other fish all look very happy and healthy and haven't shown any signs of stress of problems. If anything, they've gotten more spunky and exploratory with time.
I also worry that keeping them in the fry enclosure too long could stress them out even more, but since they're in my office at work, I don't really have a quarantine tank I can move them to.

My questions are: 1) does anyone have any ideas as to what the problem could be? 2) Is it my water conditions or more likely a disease? 3) Is there anything else I should be doing that might help the situation? More plants, more water changes? I keep hoping he comes out of it since his condition is constantly fluctuating, but today I've been especially worried since he looks worse than ever, and I'm hoping I can still do something dramatic to save him.
The tank is scheduled for a water change this evening, but is it better to leave as is for a while since the levels haven't really improved or worsened?
I'm just trying to avoid anything that might push him over the edge since the poor guy has already been through so much in just the last week and a half.
Any ideas or suggestions would be greatly appreciated.
Thank you for bearing with me through this lengthy post!


It's hard to say for sure, especially without pictures or video, but I can take a stab at it.
Obviously getting stuck to the intake slits is bad, but more a sympyom, since they should usually be able to pull away. In general I'd recommend an intake spoke or prefilled to prevent it from happening again.
As to why it happened, I'm sure the shock of going from a cycled tank to an uncycled tank, plus not being fed enough (cycled or uncycled, your fish need food,) has caused enormous stress, which in turn could easily make them susceptible to illness. Feeding your fish every day, except for maybe one day for fasting, is best to keep them strong. And as long as you're not overfeeding, it will help cycle the tank, you may just have to do more water changes in the meantime. Any nitrites at all says your cycle is doing good, but you also need to get them as low as possible with water changing. Nitrites are much more toxic than nitrates and even in low numbers can hurt your fish.
As long as they're not stressed more by it, a breeder net is a good place for now to keep the weakest from being picked on. From your description, I'd say they are younger. At my store we have both older and younger ones and often the older ones establish dominance and its a struggle for the smaller ones to eat and not be picked at. You may have to leave them in the breeder net until they get stronger, larger and more able to keep up and defend themselves, as it's possible they're also being bullied when you're not looking. For now it's just keeping the water clean, making sure they're fed and observing for any changes. As for the spine I can't say without a picture :/


It's hard to say, as Savanna says, without visuals. I personally don't mind their low feeding schedule, so long as they are generally eating well and looking healthy. Naturally, fish are opportunistic eaters and have to be able to go a week or so without food, and that capability won't necessarily disappear while breeding in captivity. Unless you really control how much you feed your fish, it's probably considered bad to feed your fish more than once everyday. This is of course with the exception of fry; I believe fry are usually produced when food is rather abundant among other circumstances.

I would think it's just a birth defect / abnormality. I don't know if GloFish continuously inject DNA into fertilized Zebra Danio eggs for every single batch or if they breed them. I would think breeding them would be likely, and my guess is that it's possible that there could be some inbreeding happening. Sometimes deformities can result from inbreeding.

It's great that you have them segregated in a breeder net and you're doing the best that you can. The only thing I could advise would be more regular water changes to manage lower levels of Nitrite because that is definitely not going to help the situation. It is toxic even in small doses. Otherwise, if he continues to decline then maybe euthanizing him would be best to end his suffering.


Thank you both very much for your replies! Unfortunately, the one little green guy passed away yesterday. Tonight, the other green guy wasn't looking too good. Started exhibiting the same symptoms as the other one. I gave him a treatment of methylene blue (in a separate container, not the main tank), and he already seems better than he was just a couple of hours ago. Still not totally out of the woods, though. He's currently in the breeding net. The other fish are swimming around normally and look good, but they didn't want to eat when I fed them. Didn't even really react to it aside from a couple of them that did eat. I've been giving them regular flakes as well as some of the Spectrum pellets. I generally put the food in a cup with their tank water and swirl it around to try and avoid them sucking in air, and then I pour that into the tank. Needless to say, I only poured a small amount once I realized they weren't interested so there wouldn't be an excess of uneaten food left behind. Normally, I feed them in the daytime, and today I fed them late at night, so I don't know if that contributed to their lack of interest. I retested the water, and it's now at 0 ammonia, 0 nitrities, and somewhere between 5 and 10 nitrates (the result was a little darker than the 5, but lighter than the 10). Since they appear to be in good physical shape, I'm hoping it's just an episode and they'll be better the next time I try and feed them, but I'm worried there could be some relation to the issues the green guys have been having. Unfortunately, I was unable to post a photo, for some reason. If I can get one, I'll include. I have to leave my office now, but I'll be back tomorrow afternoon to check on them and the water conditions again.

Similar Aquarium Threads

  • Question
  • Question

Random Great Thread!

Latest Aquarium Threads

Top Bottom