Blushing Tetra Not Eating, Lethargic

  • #1
Details on the situation are at the bottom, after the "sick fish" form.


What is the water volume of the tank?
20 gallon
Does it have a filter?
Does it have a heater?
What is the water temperature?
80 F
What is the entire stocking of this tank?
3 blushing tetras (planning to add more as soon as I figure out what is wrong with the sick one), 1 dwarf gourami


How often do you change the water?
Once a week (more frequently while cycling)
How much of the water do you change? 25%
What do you use to treat your water? Seachem Prime
Do you vacuum the substrate or just the water? Vacuum gravel


Did you cycle your tank before adding fish?
I'm just finishing cycling now. I used Seachem Stability, and Seachem Prime was added every couple days to detoxify ammonia/nitrite along with water changes every 3-4 days. I never saw ammonia/nitrite readings over 0.25 ppm (testing twice a day for the majority of the fish-in cycle).
What do you use to test the water? API Freshwater Master Test Kit
What are your parameters? We need the exact numbers, not just “fine” or “safe”.

0 ppm
Nitrite: 0.25 ppm
Nitrate: 5 ppm
pH: 7-7.5


How often do you feed your fish?
Once a day in the morning.
How much do you feed your fish?
As much as they'll eat in a couple minutes.
What brand of food do you feed your fish? Northfin and New Life Spectrum.
Do you feed frozen or freeze-dried foods?
Not yet but I'm planning to incorporate them eventually.

Illness & Symptoms:

How long have you had this fish?
Just over 1 week
How long ago did you first notice these symptoms? Just noticed in the last 3 or 4 days, but may have been ill longer.
In a few words, (more room for details below) what are the symptoms? Not eating, hovering at the back of the tank instead of swimming with other tetras, lethargic, dark spot in intestines?
Have you started any treatment for the illness? I tried feeding peas but he wouldn't eat those either.
Was your fish physically ill or injured upon purchase? Not sure.
How has its behavior and appearance changed, if at all? He has gotten more "antisocial" (he used to swim with other tetras - he doesn't anymore) and lethargic.

Please explain your emergency in the best detail possible.

I've had my tank set up for about 2.5 weeks. I got the dwarf gourami shortly after setting it up (I know, fish-in cycles are evil but this is my first aquarium and I knew a lot less 2 weeks ago than I do now). I added the 3 blushing tetras a week after that, about 1.5 weeks ago. I think my tank is almost done cycling based on the parameters, but my ammonia and nitrite have been low throughout the process. I don't think the illness is due to the water parameters because my other fish (even those of the same species) seem happy and healthy - they are eating, active, bright, and generally not exhibiting any of the symptoms of the sick fish.

A few days ago I realised one of the blushing tetras is not eating - tbh I'm not sure if he's eaten since I got him home because it took me a while to get the tetras eating at all. The first the food was too big and then they didn't like the new brand of smaller food I bought for them, but they really love the crush NLS pellets and will now occasionally eat the smaller Northfin ones too. So I didn't realise he wasn't eating until the other two started eating like pigs. He also hangs out at the back of the tank behind decorations and among plants, and he has stopped cruising around the tank with my two other tetras. He seems lethargic and occasionally seems to be breathing heavily. I've also noticed a dark spot on his abdomen that seems to be in his guts (this spot isn't on my other tetras even shortly after feeding - see pics 6412 and 6413 vs. pic 6414 of healthy tetra).

This morning I put him in a cup filled with water directly from the tank (same temp, same parameters, not washed with soap, etc.) to get a better look at him. Immediately after I put him in the cup, he lay on the bottom on his side for a minute or so before swimming around frantically. I thought the dark spot on his gut might mean constipation, so I tried feeding him peas in the cup but he wouldn't eat them. Then put him back in the tank and dropped in a crushed pea. My other fish loved it, but the sick one only seemed mildly interested (hovered around it, didn't eat any) before returning to the back of the tank.

He's smaller than my other two tetras and has seemed a bit off since I got him but symptoms have definitely gotten worse in the past week and it's the not eating that's really worrying me. I'm not even sure if this is a chronic thing or something that started after I got him. I don't have a quarantine tank and am worried about him dying overnight and creating an ammonia spike that kills my other fish since the tank is so newly cycled. Should I try some a treatment, talk to the fish store, or just wait it out?


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  • #2
If it's only been a week I wouldn't worry yet. New fish are going to be very stressed and tend to not eat for several days. I had one not eat for a whole 2 weeks once. I'd put him back in the tank, especially if you can't heat the cup

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  • #3
If it's only been a week I wouldn't worry yet. New fish are going to be very stressed and tend to not eat for several days. I had one not eat for a whole 2 weeks once. I'd put him back in the tank, especially if you can't heat the cup

Yes, he's back in the tank. He was only in the cup for 20 minutes or so so I could get a closer look and take some pictures. I'm just worried because I'm new at this and he's acting so differently from my other fish.
  • #4
I don't see anything wrong with him, kinda helpful that he's almost 100% see through. I think it's just stress
  • #5
Have you tried feeding him some frozen foods or soaking his food in garlic guard?

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