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Fish death after feeding baby brine shrimp

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Calamardo Tentaculos

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Hi all,

Just want to get your thoughts as I have a spate of deaths in my tank after feeding my fish baby brine shrimp (BBS)

I've recently introduced 6 pygmy cories into my tank. Two days ago I fed them some baby brine shrimp. Today I found two of them dead with signs of bloat.

Strangely all the existing fish in my tank including the existing pygmy cories were unaffected. Only the new ones were affected.

Could this be the salinity from the BBS? I did rinse them with tap water but it's my first time so I may not have done it correctly. Or, could it be overfeeding?
 
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New fish should be quarantined for a month before release. Many people will also pre-treat: <"With the amount of wild caught fish circulating fish stores, I think avoiding parasites is near impossible, and ever since medicating the new arrivals in quarantine, my tank has been far healthier and happier">. When parasitic worms are present: the gut blocks, becomes inflamed, and infection takes hold. These fish are more susceptible to overfeeding but it is not the root cause. If parasitic worms have contaminated the tank then fenbendazole might be suitable as a treatment because it will target worms and is <less likely to affect beneficial bacteria>. Salinity of rinsed live baby brine shrimp is unlikely to be a factor.

Also, frozen commercial foods can thaw repeatedly before point of sale and are notorious for poisoning fish. Clean safe cultures of live foods are a lot easier in the long run. I don't bother with brine shrimp eggs because I am not in control of their production. At this time of year I would be collecting small bloodworm from rainwater buckets and any small mayflies. I would chop Californian blackwoms before feeding and using clean homegrown cultures of tubifex. Sparingly I would use grindal worms from very clean cultures. I would have frozen bags of clean safe aphids, mosquitto larvae, or whatever I collected the previous summer, and of course some good quality dry processed foods. I think they will possibly chase and consume daphnia if you culture them.

Feeding is like presenting carrots to a horse, but I don't think this is what went wrong - it's not you that got it wrong, it's your supplier, so don't be put off.
 
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Thanks @Simon Cole. It was live BBS so not frozen, but I agree on quarantining and will be doing that from now on.

You might be right regarding the parasites, but they were lively for the first two days and deaths occurred two days after the BBS were fed to the tank.

If this persists, I will treat the tank with flukesolve. I have flubendazole but can't use it due to the amano shrimps in my tank. Is fenbendazole shrimp safe?
 
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Yeah, I also doubt that the BBS was the problem. Corys can take more salt than would come in with washed BBS, and new fish are notorious for bringing any number of maladies with them. With the added stress of moving to a new environment there can be a high risk of death. I quarantine new stuff for 4 weeks and have managed to keep all the trials and tribulations of new fish out of my main tank, but sometimes there are still losses during that period.
 
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Calamardo Tentaculos said:
Sigh, looks like I will have to treat my tank then.

Any recommendations for levamisole & metronidazole products? As I recall, the latter is an antibiotic and not for sale in the UK, but I may be mistaken.
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I would definitely not recommend treating the tank without a diagnosis.

If, for example, internal parasites are present (which is very unlikely to be the case), then it will only help if the medication is mixed in the food. An effective medication would be Fenbendazole or similar. And then you need to know how to do this correctly and safely.

When you have a diagnosis, we can talk about how to do this. I have successfully carried out several treatments against internal parasites and I can tell you that this is not a game for the uninformed or beginners. I repeat again: do nothing at the moment and observe the fish. The fish will show you if they are healthy.
 
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Gerald Bassleer, The new illustrated guide to fish diseases, first edition, ISBN 90-807831-2-9, Page 221-222:

Levamisole:
long bath 200 mg per100 litres for 24-48 hours.
Repeat treatment after two or three weeks.
200 mg per 100 grams fish food for 5 to 7 days.

Fenbendazole:
long bath 200 mg per 100 litres for 2 days.
Repeat treatment after one week and again after two weeks.
Change water after treatment.
200 mg per 100 grams fish food for 5 days, to be repeated after 2 weeks.
---------------------------------------------------------------------------------

Fembendazole is preferred and it is available in the UK.
Metronidazole I would skip because it will nuke bacteria.
I would not bother with solvents to dissolve treatments. Just mix either choice into suspension and pour in.
I tend to add treatments in powdered form to flake food, shake them, and let them sit overnight before feeding.

Baths:
Baths need to be heavily aerated, and I feel sponge filters are less disruptive to fish.
Temperature 22 degrees Celsius.
Remove activated carbon, purigen and anything absorbent. Pebbles are ideal for hiding spots. Wood and leaves - no.
Ambient lighting and a quiet spot should work well.
Grab a 30cm low-iron cube and reuse the tank for another project.

Sterilising the main tank:
I would use the dosages provided by Edward J. Noga, Fish Disease: Diagnosis and Treatment, Second Edition, ISBN-13: 9780813806976 because they are slightly higher.
Remove fish to the quarantine tank with the lower dosage beforehand.
For Fenbendazole - a 12 hour treatment at 2.5 g per 100 litres. You can do this while your fish are away in quarantine. Repeat when they go into quarantine each time (x3) and change the water before reintroduction.
Chuck out any activated carbon, but you can bleach your purigen, and you can leave everything else in place.
I don't know what to do about your shrimp and snails - these treatments are persistent and <reported to harm snails>.
You might just as well move your corydoras to a breeding tank (repurpose the quarantine tank) and rescape, or rethink whether you need fish in there at all.

Sterilise nets, tool etc. with bleach.

You can see why most retailers wouldn't bother with the above because vets and meds aren't cheap. I kind of agree that you should wait and observe, but it's not because the method is excessively detrimental. It's more a question of effort vs reward and sometimes it is better to sterilise things down and start again. It might just be a constipation fatality (Elvis Presley), but like my comments above, this is all guess work. It goes to show that all those recommendations for quarantine tanks in the old books have stood the test of time. They are an absolute necessity.
 
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