New Rummynose Tetras dying in quarantine

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Aquarium Advice Apprentice
Jun 27, 2021
Hi all,

3 days ago I purchased 8 new rummynose tetras and 8 new hengeli rasboras to add to my tropical community tank. I've added them to my 20L / 5 gal quarantine tank for 2 weeks before introducing them to the 200L / 50 gal community tank. The quarantine tank has been cycling for about 3 weeks with filter media from my community tank before adding the new fish, so it appears to be fully established. I also have added around 10 red cherry shrimp to the quarantine tank to help cleanup food while they're in quarantine.

Overnight, 3 of the rummynose have died suddenly. Yesterday evening, I saw one of them swimming erratically - rotating upside down, lying on the bottom, not being able to swim upright properly. I tried giving it a 15m soak in an epsom salt bath in case it was a swim bladder/constipation issue before adding him back into quarantine. When I looked at the quarantine tank this morning, I saw 3 rummynose already dead. No other obvious signs of disease other than that 1 that was swimming strangely. None of the rasboras are showing any signs of illness. For now, none of the other rummynose are also showing any signs of illness. Alll the fish look to be shy but have been eating flakes and pellets.

Water parameters are 24C / 75F, 0 Ammonia, 0 Nitrites, 5-10 Nitrates, ~7.8pH. I know the pH is a little high but the water in my area is a bit hard and I've been using the same water in my community tank for 2 years with other tetras.

I've added some melafix/primafix to quarantine and will probably do a 50% water change today but is there anything else I can try or lookout for? Maybe adding some aquarium salt to quarantine? I didn't originally want to add any salt as I wanted the quarantine tank conditions to match the community tank as much as possible and there's no salt in the community tank.
The 5 gal is a bit too small for that many fish at one time, especially rummynoses. They need space, warmer temps and do better in larger schools. Also, rummynose are a fragile specie so possibly it's nothing more than the fish couldn't handle your tank size. How long were the fish in the place you got them from? If they were new arrivals to there then you got them, that's a lot of stress on a fragile specie. FYI: There are 3 species that are called rummynose and none of them are overly hardy when first received. Whenever possible, you want to get wild ones but if your only choice is farm raised, you want to get them after they have been at your retailer for at least a week ( longer for wild ones.)

Other points: if you added filter material from your main tank to the quarantine tank but did not add any ammonia or ammonia producers in the 3 weeks, you were killing off the nitrifying microbes and you may have had an ammonia spike that killed these new fish which was countered by whatever live microbes were still alive which is why you now have a 0 ammonia & nitrite level and a small nitrate level ( unless the nitrates came from your source water.) Did you check the water parameters in the QT before adding the fish?
I would not add salt to the water. A QT should be just a miniature version of your main tank regarding water parameters, temperature, feeding times, lighting times and maintenance schedule.
Since you say that the other fish (including the 3 other rummys) are eating, that's a good sign and I wouldn't do anything more than the water change and possibly adding botanicals like Almond leaves or alder cones, etc to the tank and not the mela or primafix. ( FYI, swim bladder is not really curable so the epsom salt bath would not have helped even if that was the cause in the one fish. ) If these 3 rummies survive, I would consider setting up at least a 30" long tank as a quarantine then get yourself another 6 to add to the school. I suggest using the same source so that you get the same species as before. Keep your eye in these remaining fish for ICH since your temp is a bit low for the rummies.

Hope this helps. (y)
Thanks for the additional advice. Didn't realise that Rummynose were so fragile when new! Also, a typo in my original post - there were 9 rummynose originally, with 3 dead which now leaves 6 rummynose plus the 8 new rasboras that are still looking fine as well. Yeah I thought 5 gal is a bit small but it's the only other tank I have for quarantine. I figured it would be OK temporarily for just 2 weeks if I keep on top of water changes (maybe 50% twice a week?).

My main tank is a 3ft / 1m where I do 30-40% water changes every week, with gravel cleaning every other week.

I'm not sure which exact species it is, how long they've been in the shop or if they're farm/wild (didn't end up asking). I'm in Australia so most likely they have been farmed locally somewhere due to the strict biosecurity rules we have here.

For the 3 weeks while the tank has been sitting there, I did actually have ~10 red cherry shrimp in there and were feeding them pellets every couple days, as well as 1 Indian Almond leaf that has half disintegrated by now. It's still currently there with the quarantined fishes, which I will probably replace this week once this one is a bit more disintegrated. I usually have around 5 leaves in the community tank at any one time as well so it should match relatively closely.

I know it's not a lot but hopefully it should have kept the bacteria ticking along. Unfortunately, I didn't check the parameters before beginning quarantine, only today after I found the 3 dead. This was probably around 60 hours since I first introduced them to the quarantine tank.

Thanks for the confirmation on salt - I was thinking the same thing that it should match the community tank as much as possible. Won't add any for now.

For now, I've bumped up the temp a bit by 1C so it's at around 25C / 77F, is that a comfy temp for them?

Is there any harm to keeping up the dosage of primafix/melafix in case there is some sort of bacteria/infection that I haven't seen?
Do a 30% water change to remove anything you added and don't add anything else to the quarantine tank.
Make sure any new water is free of chlorine/ chloramine before it's added to the tank.
Make sure the pH and temperature are the same as the tank too.

Post some pictures of the fish and turn the tank light off. Just have room light or open curtains providing light for a week or two.

Rummynose tetras come into Australia from Asian fish farms or are wild caught, usually fish farms though. They are regularly bred and kept in soft acidic water and if the shop only just got the fish in, and you bought them within a week of the shop getting them, the fish are probably dying from the stress of travel and significantly different water chemistry. It used to happen for about 3 months a year. We got in rummynose and they went into well established tanks and would die if you look at them the wrong way. When this started happening, we turned off the lights, didn't do any water changes for a couple of weeks, and didn't sell anything from that tank. The fish were left to recover from the stress and after a few weeks, we started doing small water changes (10-15%) and added light but had half the tank covered with polystyrene foam to stop the entire tank being lit up. A few weeks later we increased the light and started selling them.

I'm not sure why it only happens for a few months each year but it was definitely cyclical and always affected new rummynose tetras during that time. the rest of the year they were fine and didn't have any issues.
I'll defer to Colin on this one since he too is in Australia so his experiences with them would be more local to you. I'm in the U.S. and was an importer of Wild ones but since that time, Asian farms are now producing them.

I will add that since you had the shrimp and food in the tank during that 3 week period, there was an ammonia source present so the Ammonia spike theory is probably NOT what happened. How much tho would only have been known if you had tested your water prior to adding the new fish. It sounds like this is an overcrowding/fish issue rather than a disease issue so adding medicines would not have solved what happened. I would look into a larger tank for quarantine. (y)
Thanks both, and especially your experiences with new Rummynoses Colin. I've done the water change and I definitely add dechlorinator (seachem prime) to all water I add my fish tanks. The water source and pH, temp is the same for my main and quarantine tanks. The quarantine tank is only on natural light on my laundry bench which is reasonably bright but no direct light.

The rummynose still seem quite nervous and shy. They were eating the first few days but now seem to be less interested in eating but I think they are still getting a little nibble here and there. They all appear to be OK, maybe a little light on colouration due to stress. Photos posted below. All 8 new rasboras are looking totally fine and are eating well.

For now, I'm putting this one down to stress of new environment and maybe tank too small. How bad of an idea is it to end quarantine early for the rummy-nose and transfer them to my main tank this weekend after 1 week instead of 2? They will have much more room and many more places to hide as my main tank is a 3 foot/1m, 50 gal/200L with plenty of plants, rocks and driftwood. Would be more comfortable for them.


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Don't move them yet. They need time to settle down and if you chase them or stress them in any way, they could die. Give them at least 2 more weeks and preferably 4 weeks. They need to get over the stress before being moved.

You need something on the bottom of the tank. A thin layer of dark sand or gravel would make them feel much more comfortable and reduce glare in the tank. You only need enough substrate to stop the fish seeing the glass.
Thanks Colin. I’ll leave them there for a few weeks longer.

Great tip about the gravel! I added some dark pebbles to the tank and they almost immediately looked less stressed and more relaxed. They’re no longer darting around so much and look to be eating well again.

I tested the water again today, and saw a small amount of ammonia, maybe 0.25ppm just above 0 so I did another water change around 40%, removed the rotted almond leaf, added a new one and also added a little more porous media from my main filter into the quarantine filter.

Will test again over the next couple days and continue more water changes if needed.
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