# Cory cats and shrimp a bad combo?



## Atom (Sep 17, 2014)

Hi everyone,

when I researched this topic I usually got threads about people worried that cory cats are eating their shrimp. However, I'm worried about the opposite (shrimp eating cory cats).

My reasoning is that, unfortunately, another one of my corys was acting a bit lethargic and looking pale with clamped fins. I have no idea where I'm going wrong with these fish , but I've had this one since October of last year and suddenly it's gotten sick.

I figured maybe it was getting pushed around by the faster fish in the main tank and/or getting out competed for food so I transferred it to a smaller tank with a single tetra and 5 red cherry shrimp. Immediately, a shrimp came over and grabbed and dragged the cory a short distance away so I took it out of the tank and placed it alone in a breeder box. From here I noticed the cory's fins were slightly ragged :\ as if it may have been nipped at.

No other fish in my aquarium have ragged or jagged fins and the one fish I bought who had that issue (nipped fin, chunk was missing) managed to heal itself over time within the tank so I'm not sure if it's a disease that caused this. 

Overall, could it be possible that the cory was stressed and tired by fast moving fish in my aquarium and was then harassed by shrimp when it attempted to rest? This isn't the first time I've seen shrimp climbing on and dragging a cory catfish (or another sick/lethargic fish) so I'm starting to get suspicious. Or is it possible that shrimp only go for fish that are already past the point of return?

Thanks in advance and sorry for the text-heavy post.


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## cb1021 (Sep 21, 2009)

That's hilarious - I wonder too what's going on. 

What do I do notice/assume is that your tank's not planted right?? Even at the aquarium shops, fish are simply healthier when they're in a planted aquarium. Perhaps it's time to take the plunge.


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## Atom (Sep 17, 2014)

The catfish has since died in the breeder box :\

Sorry I'm still fairly new so I'm not entirely sure what you mean by "planted tank". The substrate is inert so I don't have any plants growing in it, but I do have live java moss so I'm not sure if that counts as a plant 

I'm trying to get a few more basic (substrate-free) plants to help with water quality and add more shelter for the fish in the near future.


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## Bullet (Apr 19, 2014)

I'm not a shrimp guy but I currently keep and breed several species of cory
I am very sorry to hear about your cory's passing 
If I can ever help with the quarantining, healing etc of any current or future cory that you have, please PM me and I will be more than happy to help


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## Atom (Sep 17, 2014)

Thanks for the kind offer Bullet 

It's getting a bit discouraging to be honest. I hadn't noticed the ragged fins until today and it seemed like it was already too late :\

All the corys I've had seem to be of the bronze variety and are fairly young (around 1 inch long) so I'm not sure if that makes them hardier or more delicate than other species or older ones. 

Maybe I should've posted this in the "Beginners" section  I was debating between "Catfish" and "Invertebrates" and totally forgot about it.


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## Bullet (Apr 19, 2014)

Atom said:


> Thanks for the kind offer Bullet
> 
> It's getting a bit discouraging to be honest. I hadn't noticed the ragged fins until today and it seemed like it was already too late :\
> 
> ...


No need to get discouraged - we are dealing with live animals in this hobby so it will always be challenging but we need to do our best. There are no silly questions on this forum

Bronze corys are quite hardy and 1 inch size are still young

All good for your posting - there are some great shrimp guys on this forum - check out a member named woopderson for shrimps


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## zfarsh (Apr 7, 2011)

1) red chery shrimps are harmless to fish.

2) post your parameters always when asking for assistance in troubleshooting.

- tank size (gallons)
- inhabitants
- planted or none ( planted means a large portion of your tank is covered with plants )
- how old is your tank in term of having it setup.

Now comes the big dreaded questions:
- what is your ammonia and nitrite readings. If you happen not to know what this means, then I recommend starting here and reading on this first. 
- if the above is ok, then when did you get the fish, and from where, and more importantly, have you quarantined them? If not familiar with any of this, then it is a good time as any to research this subject next. By the way, fish can be sick from the aquarium stores, and spread their disease to other fish,
Note: the above 2 are the foundation and starting points....


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## Atom (Sep 17, 2014)

Hey zfarsh thanks for responding despite this being quite an old thread. 

My mistake on not listing the parameters of my tank. I think at the time I was convinced it was mostly a shrimp-catfish interaction and was a bit panicked as well. 

Since the corycats' deaths, my tank hasn't experienced any other problems. When I received the corys I didn't have the means to quarantine my fish so I just drip acclimated them, put them in the tank and hoped for the best (not the best practice, but the best I could do at the time). 

The corys were from Big Al's during a sale and the tank was somewhat crowded with some dead fish so it's possible some were sick. Nevertheless, 1 out of 3 of the fish I got from that sale is still alive and well in my tank so I wouldn't put too much blame on Big Al's for the fishes' outcome as they looked mostly healthy when I bought them with only some partially missing fins. EDIT: actually one of the corys that died was an albino one I got from Petsmart in October. The other two that died (one unrelated to this shrimp issue) were from Big Al's.

Today I have my main 20g (running since Oct 2014) and a smaller 5.5g (running since mid Jan 2015) to house fry and shrimp. The main tank has a guppy, several cherry shrimp, 11 minnows, 7 neon tetras, 1 cory, 4 otos, and 6 zebra danios. I'm aware that it's getting a bit crowded and have been trying to give away some minnows with no luck :\.

In terms of plants, there are floating frogbits, hornwort, and java moss. 

Ammonia and nitrite are considered "trace" (<0.02 ppm) and 30% water changes were done every 1-2 weeks. All other parameters were deemed "ideal" by test strips (again, not the most accurate, but probably not detrimental if my levels are within the "ideal" range).

At this point, I would suspect the deaths were due to crowding/stress by the more aggressive fish leading to the possibility that the corys weren't getting enough food in addition to maybe being sick already. The shrimps may have been able to detect that the catfish were ill and attempted to scavenge on them while the fish were already weakened. It just looked so dramatic when I plopped a corycat into the other tank and it got swarmed by shrimp while resting on the bottom.


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## zfarsh (Apr 7, 2011)

For the cories, I think the fact that were from big al and likely sick is the reason of death.

There is a member here, bwhiskered I believe, who was a breeder for cories. Also, menagerie usually has healthy stock. I would recommend these 2 for new fish, or getting them from fellow members selling them.

Now, I am not sure if you are over crowded, but got the feeling you might be. I personaly get away with it as tanks are fully planted, but there is a limit to that too.

The shrimps, red cherry, will only eat fish if it is death or near death. Only ghost shrimps are more aggressive.


Anyways, good luck with your tank, glad to hear it is more stable now.


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## solarz (Aug 31, 2010)

Atom said:


> Today I have my main 20g (running since Oct 2014) and a smaller 5.5g (running since mid Jan 2015) to house fry and shrimp. The main tank has a guppy, several cherry shrimp, 11 minnows, 7 neon tetras, 1 cory, 4 otos, and 6 zebra danios. I'm aware that it's getting a bit crowded and have been trying to give away some minnows with no luck :\.
> 
> In terms of plants, there are floating frogbits, hornwort, and java moss.
> 
> ...


If you have *any* detectable amount of ammonia and nitrites, it means your tank is not cycled yet. If this is happening in your 20g, then that means something is disrupting the biofilter, as it should have cycled after this long.

When you say "all other parameters are ideal", what do you mean, exactly? More specifically, what is your nitrate level?

Are you perchance rinsing your filter media in tap water? How much hornwort and java moss do you have in there?

Finally, I would be amazed if a cherry shrimp could drag a cory. Are you sure you have a cherry shrimp in there?

If you can provide a picture of your tank, it would be a lot more informative!


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## zfarsh (Apr 7, 2011)

All good points by solarz


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## Atom (Sep 17, 2014)

I erred on the side of caution by saying "trace" because the colour was reading as "0"-ish to about around 0.02 ppm. This level of ammonia usually would be considered "0" under any other tests and I'm not sure how close to true zero one could get so I estimated within the higher range of what I possibly had. Since the infamous "what colour is this dress" stuff has come out, it's possible that I could've seen the colour-reading as yellow instead of blue or something 

The other parameters were: pH, KH, GH, and nitrate. I don't recall the exact levels of nitrate, but they were creeping into unsafe levels so a water change was recommended and done at the time. I have no idea what my TDS is though 

I'm not sure if it's entirely a chemical problem or I might've seen deaths on a larger scale or at least symptoms of poisoning (fish dashing for air at the surface, redness around gills, discolouration, etc). I also keep some species (otos, neon tetras, cherry shrimp) that are considered "sensitive" by some to poor water quality and have only had the loss of 2 shrimp out of 30 within that group most likely due to age. Certain fish have also been bought with or received fin tears/chunks missing and had healed within a week, which also has been said to require good water quality so I'm not entirely convinced it's mostly to blame in this case. 

Since running the aquarium with fish, I haven't rinsed the filter media in tap water. I run an AC50 with a sponge pre-filter and foam and a nylon scrubber in the basket. When I perform a water change, I rinse the pre-filter, foam, and basket in a bucket of drained aquarium water. 

In terms of how much hornwort and java moss, I didn't have the hornwort at the time, but had about a soccer ball sized loose clump of java moss. No pictures at the moment  my tank is completely disorganized with tangled hornwort and moss.

I was surprised as well that the cherry shrimp could move the cory. There were a few of them around the cory cat and although it was a young-ish, small (1.5 inches) cory, they managed to move it at least a cm or two before I fished it back out.


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## solarz (Aug 31, 2010)

Atom said:


> I erred on the side of caution by saying "trace" because the colour was reading as "0"-ish to about around 0.02 ppm. This level of ammonia usually would be considered "0" under any other tests and I'm not sure how close to true zero one could get so I estimated within the higher range of what I possibly had. Since the infamous "what colour is this dress" stuff has come out, it's possible that I could've seen the colour-reading as yellow instead of blue or something
> 
> The other parameters were: pH, KH, GH, and nitrate. I don't recall the exact levels of nitrate, but they were creeping into unsafe levels so a water change was recommended and done at the time. I have no idea what my TDS is though
> 
> ...


If you are seeing nitrates, then you shouldn't have any problem with ammonia and nitrite. Depending on how much light you have, you may simply be overstocked. A nitrate level would be useful to know. If it's over 40ppm, then that might be your culprit.

No healthy fish will let it self be dragged by cherry shrimp. Chances are, your cory was dying already.


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## Atom (Sep 17, 2014)

The cory was definitely already sick. 

The ones in the main tank tried to swim away from shrimp, but as soon as it came to rest on the bottom, more shrimp would bother it. I think on top of the cory already being ill, this extra stress didn't help. The shrimp don't seem to be bothering my last remaining cory though  at least not to the extent that I noticed before. 

I'm definitely overstocked. If anyone wants some minnows or guppies let me know! I don't think it was the chemical influence of the overstocking, but more so the stress and food competition it created in the tank. The corys might've just been too passive in comparison to the other fish during feeding time unfortunately.

Regardless, I'm eager to do another water test soon as well as a check on my TDS because I still haven't seen any of my shrimp berried


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## solarz (Aug 31, 2010)

Atom said:


> The cory was definitely already sick.
> 
> The ones in the main tank tried to swim away from shrimp, but as soon as it came to rest on the bottom, more shrimp would bother it. I think on top of the cory already being ill, this extra stress didn't help. The shrimp don't seem to be bothering my last remaining cory though  at least not to the extent that I noticed before.
> 
> ...


I'm not sure what you mean by "chemical influence", but high nitrates will compromise a fish's immune system, making them more likely to get sick and die.

IMO, you are reading too much into "stress" and food competition. None of the fish you listed are aggressive. I've had planted 20g tanks that held even more fish. At one point, I had 10 white clouds, 10 harlequin rasboras, 20 cardinal tetras, 3 cories, and 3 otos, along with 2 amano shrimps and countless cherry shrimps. In a previous incarnation of that same tank, also planted, I had 30 cardinal tetra, 2 siamese algae eaters, 6 adult guppies, dozens of fries, 6 amano shrimps, and countless cherries.

The key word here is planted. The more plants you have, and the faster they grow, the more nitrates they will absorb, and thus the less nitrates you will have in the water. Less nitrates = healthier fish.

The same thing applies to shrimp. Cherries will survive less than ideal water conditions, but they will not reproduce. Cherries don't care about TDS very much, but they won't thrive if nitrates are too high.


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## Atom (Sep 17, 2014)

Agreed on nitrates leading to fish being more susceptible to illness, but if that's the case wouldn't more fish be dying off or showing symptoms of nitrate poisoning?  I won't know for sure until I get the water tested again, but I'm just curious as to why it's only been hitting the corys so hard and the other fish appear fine for now.

I've actually got rosy red minnows and there are a few large (~3 inches) ones that love to swim really fast around the tank and occasionally will bump into other fish. The pellets I put in for the corys are usually swarmed by a ball of the minnows and while I know they aren't necessarily aggressive in nature, they're definitely more assertive when it comes to food. 

That on top of getting picked at or climbed on by shrimp while coming to rest would seem like a stressful situation, which wouldn't aid in recovery either. I'm not suggesting that the shrimp would ever be entirely to blame, but it didn't seem like they helped the situation. They're scavengers by nature so they could've just been doing their job.

You touched upon the reason I opted to get more plants (hornwort and frogbit) because I had heard that they're good at taking up excess nitrates. I know that's no substitute for water changes, but I figured it would be a good addition to the tank anyway. 

The shrimp have been breeding lately and I'm hoping they'll be more active now that winter is ending (some have observed that they cease breeding during winter), but I haven't seen any sign of berrying still. People have suggested that they may hide more often or be more likely to drop eggs in a tank with fish because they're seen as predators, but who knows  

Would I be able to give my minnows back to a LFS or would they dispose of them? Ideally I want to re-home them, but no one seems interested :\


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## solarz (Aug 31, 2010)

Atom said:


> Agreed on nitrates leading to fish being more susceptible to illness, but if that's the case wouldn't more fish be dying off or showing symptoms of nitrate poisoning?  I won't know for sure until I get the water tested again, but I'm just curious as to why it's only been hitting the corys so hard and the other fish appear fine for now.
> 
> I've actually got rosy red minnows and there are a few large (~3 inches) ones that love to swim really fast around the tank and occasionally will bump into other fish. The pellets I put in for the corys are usually swarmed by a ball of the minnows and while I know they aren't necessarily aggressive in nature, they're definitely more assertive when it comes to food.
> 
> ...


Funny you should mention rosy red minnows, because they're among the most nitrate-resistant fishes. They actually do nitrate toxicity studies using those fishes! 

http://onlinelibrary.wiley.com/doi/10.1002/etc.5620191211/abstract


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## Atom (Sep 17, 2014)

Interesting =o well they've survived the 2nd longest (1st place goes to the danios) and seem fairly hardy for "feeder fish".

Will update if anything goes wrong in the near future or if anything weird shows up on the next water test I do.


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## Jeff B (Jul 27, 2010)

solarz said:


> Funny you should mention rosy red minnows, because they're among the most nitrate-resistant fishes. They actually do nitrate toxicity studies using those fishes!
> 
> http://onlinelibrary.wiley.com/doi/10.1002/etc.5620191211/abstract


Yeah, they are just fathead minnows with fashion sense. Put a few dozen fathead minnows in a fishless pond in the spring and there can be hundreds in a few months. The males will get nice and brassy with a dark head. They do some interesting nest prep and egg guarding.


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## Atom (Sep 17, 2014)

Yep  still got the minnows around if anyone's opening their ponds up for the spring and would like to have a few fish and maybe observe some of that behaviour. 

My remaining catfish was acting a bit strangely and was resting in bundles of moss for a couple days. I thought it had died, but when i tried to fish it out it moved quite quickly. I decided to separate it from the other fish/shrimp and put it in a floating breeder box for 2-3 days. I didn't want to keep it in there for too long even though it was fairly spacious for the fish's size. 

For the first day it didn't eat, but then slowly regained its appetite and activity back and is now swimming around the tank and up and down the glass again. I'm not sure if it became lethargic because it wasn't getting enough food or if my gravel is too dirty for it to be resting on for long periods of time. Could've been something entirely different, but letting it hang out in the breeder box with its own source of food seems to have livened it up immensely.

Regardless, I've since done a fairly large water change with more thorough gravel vacuuming and at least now I seem to have found a "fix" for now.


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