I am a grad student doing a project on the effects of warming winter temperatures on native fish reproduction in the South Platte River. One of the fish species I am looking at are Johnny Darters. We are keeping them in 20 gallon tanks and exposing them to 3 different winter scenarios: 20 degree C, 16 degree C, and 12 degree C with the same light:dark cycles they would experience from our collection area. Anywho, my initial pathology of a subset of these guys after I took them from the river is that they have Saprolegnia, likely some Ich, and a fairly large internal and external bacterial infection. I treated them with formalin, but it did not seem very effective as many died with a visible fungal infection (Saprolegnia). I am curious if anyone here pre-treats their darters for similar issues, and if it was successful. I appreciate any input or suggestions (including unrelated input about my study). I would like to have a treatment plan of action before I bring in the darters I will use for the study.
Thanks!
Darter Temperature Experiment and Pre-Treating
Started by
Guest_UWYO_*
, Oct 24 2013 02:21 PM
29 replies to this topic
#2
Guest_EricaLyons_*
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Posted 24 October 2013 - 03:05 PM
Collection and acclimation have a lot to do with disease presentation. I've got some experience with Elassoma fuzzy-death (saprolegnia, columnaris, or some other white growth) and I've seen a dramatic difference between stressed and unstressed fish. It's funny, a fish can be totally fine but the minute the water parameters change too much for it, all of a sudden there is fuzzy death where there was none before. I've even accidentally induced symptoms in a healthy population with a 100% water change. The stress is what kills them, really.
What methods did you use to collect them? How did you transport them and how did you acclimate them to your tanks?
What methods did you use to collect them? How did you transport them and how did you acclimate them to your tanks?
#3
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Posted 24 October 2013 - 03:14 PM
Most people add 100% pure non iodized salt to their collection buckets. 2 tablespoons per five gallons is pretty sufficient. Cuts down on osmotic stress, and acts as an antibacterial, antifungal. Keep the water as cool or cooler than the water that they were collected from, and give them plenty of aeration. Slowly acclimate them to their new environment, and be sure that it is a fully cycled tank. Check your water parameters. And if you are not keeping plants in the same tank, keep up the salt for a while, if not indefinitely.
#4
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Posted 24 October 2013 - 03:30 PM
I agree, plants help. Recently I found a neat article on yarn. If you don't use plants, it's possible to use yarn to give them a place to hide and feel more secure.And if you are not keeping plants in the same tank, keep up the salt for a while, if not indefinitely.
Yarn article: http://fish-etc.com/knowledge/1174-2
(Plants are also functional, they improve water quality by removing nitrogen from the water to make new tissue. http://www.theaquari...ical_Filtration )
#5
Michael Wolfe
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Posted 24 October 2013 - 03:49 PM
UWYO,
Let me get something clear, you said "initial pathology"... are you saying that you sacrificed some individuals before they spent any time in your tank system and found the presence of the infection?
Let me get something clear, you said "initial pathology"... are you saying that you sacrificed some individuals before they spent any time in your tank system and found the presence of the infection?
Either write something worth reading or do something worth writing. - Benjamin Franklin
#6
Guest_UWYO_*
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Posted 24 October 2013 - 04:08 PM
I appreciate the input!
In response to EricaLyons: I collected them via electroshocking, which is somewhat invasive, but in my experience they fully recover. After I electrofish them, I place them in an aerated cooler and bring them back to the lab. There I replace 1 L of the water from the cooler with the water from my tanks every 15 mins for about 2 hrs. after that I just transport them directly to the tanks which I have at 12 degrees (same as what we collected them at). It is very possible that the elecrofishing method stressed them out, but they did not begin developing symptoms until 2 weeks after I brought them in. You may be exactly right that it is a stress issue, but apart from the change from the coolers to the tanks, water parameters should not be changing much.
In response to Skipjack: I have heard about the iodized salt treatment for ecto-parasites, and it may help reduce the stress and help regain their ion balance after electrofishing. I may have to try that. I do have them well aerated, and my tanks are set up on a flow through system (approx. 800ml/minute flow), so I would be very surprised if there are high ammonium concentrations. I also have spawning tiles (pieces of PVC cut in half) for some shelter. I am really leery of putting any vegetation in my tanks simply because it may fall under criticism when I present my results (I will consult my advisor). Erica's yarn idea may be acceptable.
In response to Michael Wolfe: Sorry I was unclear there. By initial pathology I mean I sacrificed some from my initial collection after I started seeing an infection.
Additional info: I have been told to use malachite green to treat these guys, but I'm pretty sure it is illegal and therefore do not want to use it(though you can buy it at Walmart). I have also been told to try hydrogen peroxide, but was warned that it may be too harsh on darters (we used it in our walleye hatchery). Does anyone have any experience with either of these?
Again, thank you so much for the input!
In response to EricaLyons: I collected them via electroshocking, which is somewhat invasive, but in my experience they fully recover. After I electrofish them, I place them in an aerated cooler and bring them back to the lab. There I replace 1 L of the water from the cooler with the water from my tanks every 15 mins for about 2 hrs. after that I just transport them directly to the tanks which I have at 12 degrees (same as what we collected them at). It is very possible that the elecrofishing method stressed them out, but they did not begin developing symptoms until 2 weeks after I brought them in. You may be exactly right that it is a stress issue, but apart from the change from the coolers to the tanks, water parameters should not be changing much.
In response to Skipjack: I have heard about the iodized salt treatment for ecto-parasites, and it may help reduce the stress and help regain their ion balance after electrofishing. I may have to try that. I do have them well aerated, and my tanks are set up on a flow through system (approx. 800ml/minute flow), so I would be very surprised if there are high ammonium concentrations. I also have spawning tiles (pieces of PVC cut in half) for some shelter. I am really leery of putting any vegetation in my tanks simply because it may fall under criticism when I present my results (I will consult my advisor). Erica's yarn idea may be acceptable.
In response to Michael Wolfe: Sorry I was unclear there. By initial pathology I mean I sacrificed some from my initial collection after I started seeing an infection.
Additional info: I have been told to use malachite green to treat these guys, but I'm pretty sure it is illegal and therefore do not want to use it(though you can buy it at Walmart). I have also been told to try hydrogen peroxide, but was warned that it may be too harsh on darters (we used it in our walleye hatchery). Does anyone have any experience with either of these?
Again, thank you so much for the input!
#7
Michael Wolfe
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Posted 24 October 2013 - 04:15 PM
OK, so if you already have these fish in a system as you describe, and you are beginning to see some infection, I would follow Skipjack's advice and seriously think about adding the salt to the system.
Either write something worth reading or do something worth writing. - Benjamin Franklin
#8
Guest_fundulus_*
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Posted 24 October 2013 - 04:58 PM
All of the above advice is correct. I will say that darters are the one fish group who don't seem to do well with shocking, maybe it's something like a higher surface to volume ratio? I'd suggest trying to collect them in a less severe fashion like with a seine.
#9
Guest_UWYO_*
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Posted 24 October 2013 - 05:33 PM
Thank you. I will definitely try the salt with my remaining fish from the initial sample. I will also try to bring some into the pathology lab before I put them in my tanks during my next collection. It may be interesting to know what they have coming straight from the river. I am re-collecting tomorrow, so I will post the results from that tomorrow if I can. I have tried seining, but the high flow rates in the river when we were initially out there made it impossible to keep the lead line on the bottom which you need to get darters. Also, in my experience seining darters from lakes (for an unrelated IBI project), they can get fairly roughed up from the nets and dragging on the bottom so I always thought shocking them was less invasive. Who knows though. I may try doing both and keeping them separate for a while to see if one method works better. I really cannot thank you guys enough for the input!
#10
Guest_Skipjack_*
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Posted 24 October 2013 - 05:56 PM
A chain attached to the bottom of a seine helps a great deal when targeting darters. It forces the mesh to follow the contours of the stream bed.
#11
Michael Wolfe
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Posted 24 October 2013 - 07:24 PM
Also, in my experience seining darters from lakes (for an unrelated IBI project), they can get fairly roughed up from the nets and dragging on the bottom so I always thought shocking them was less invasive.
I have tried seining darters in lakes, but I can tell you a lot of people here have seined the in rivers and streams (for keeping in aquariums, so we are trying to treat them very lovingly) and they do not get roughed up at all. And I have snorkeled with the fish while others were seining and I can tell you that they can swim in and out of the seine 4 times if they really wanted to (and some of them do). The ones in the seine just decided to settle into the seine. If there is any roughing up going on, I would bet it is from the actual shuffling.
Either write something worth reading or do something worth writing. - Benjamin Franklin
#12
Guest_Skipjack_*
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Posted 24 October 2013 - 08:11 PM
I would bet it is from the actual shuffling.
Almost always. I hate when it happens(rarely) but it can. If you use a soft nylon net, there should be almost no issue with damage to the fish, unless you are using a net with too large of a mesh. This can cause them to basically get gill netted.
#13
Guest_EricaLyons_*
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Posted 24 October 2013 - 09:48 PM
Regardless of its flow rate, a new filter doesn't have the nitrosomonas and nitrospira bacteria that are necessary to convert ammonia (toxic at 1 ppm) to nitrite (less toxic) to nitrate (most fish get symptoms at 30 ppm and above). Days 1-40 of initial protein exposure are subject to nonzero ammonia and nitrite.my tanks are set up on a flow through system (approx. 800ml/minute flow), so I would be very surprised if there are high ammonium concentrations.
How many days has your system had protein in it? Did you add fish flakes or ammonia in the month before adding fish?
#14
Guest_EricaLyons_*
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Posted 24 October 2013 - 09:58 PM
Is malachite green illegal? I know California recognizes it as a carcinogen, but I don't live there. I've seen it in pet stores and used it to treat external parasites a decade-ish ago. It's not really useful for fungus or gram negative bacteria. Here is a good general piece of advice when applying medication: Know what you're treating. Are you absolutely certain this is saprolegnia? Did you look at it under a microscope? Because columnaris is more common. If it is columnaris (a gram negative bacteria) and you treat it like it's saprolegnia, the medication won't help and since you'll still have side effects and now drug interactions to worry about, will make things worse. And vice versa if you treat for columnaris and it turns out to be saprolegnia.Additional info: I have been told to use malachite green to treat these guys, but I'm pretty sure it is illegal and therefore do not want to use it(though you can buy it at Walmart). I have also been told to try hydrogen peroxide, but was warned that it may be too harsh on darters (we used it in our walleye hatchery). Does anyone have any experience with either of these?
Be vary wary with hydrogen peroxide. All drugs are poisons in the wrong doses, so it's important not to use too much. The dose window of beneficial and/or non-harmful for H2O2 is very narrow. It's really easy to kill things with it instead of treating them.
I will say one thing: I have kept hundreds of fish. None of them have gotten ich when ammonia and nitrate were 0 ppm. You might want to test your water, and use a test kit that's less than a year old. Even 1 ppm is too much. Nitrate should be under 30.
#15
Guest_gerald_*
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Posted 24 October 2013 - 10:35 PM
Put salt in the collecting bucket or cooler before you start collecting, especially in soft low-conductivity water. The stress-induced loss of ions from the body (due to adrenaline) makes them susceptible to Flexibacter, Saprolegnia, and other infections, and the damage starts immediately upon capture. You need to minimize that body ion loss from the start, to avoid skin & fin necrosis and infections taking hold. Use SHORT seine hauls, just 10 - 20 seconds each; dont drag the fish around too long. Shocking darters is probably more damaging than seining. They dont necessarily die within minutes, so shocking "seems" non-lethal if you're just counting, measuring and tossing them back after a few minutes, but I think it's more damaging than the electrofishing proponents care to admit, especially on small fish like darters and shiners. We might even have a NANFA member near you who can help out with low-stress collecting-- anybody near the South Platte?.
#16
Guest_Irate Mormon_*
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Posted 24 October 2013 - 10:54 PM
What do you mean by a flow-through system? Fresh water coming into the tanks and exiting out, or is it actually a recirculating system?
#17
Guest_UWYO_*
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Posted 24 October 2013 - 11:52 PM
You guys are great! Tons of good advice. I will try to address everything, but if I miss something let me know.
In response to the ammonium/nitrate/flow through system: By flow through system, I mean I have fresh water coming into the tanks and exiting out at approx. 800ml/minute (so it ends up replacing the water in the tank something like 12+ times per day). So there is no recycling of water. Therefore I am not really worried about nitrifying bacteria Erica was referring to or high ammonia or nitrate levels. I am waiting on ammonia and nitrate probes so I can check and make sure. That graph is quite interesting Erica! Thanks.
In response to the legality of malachite green: The law states that malachite green can no longer be applied to fish for consumption or non consumption. There has to be some loophole/grey area though because it is sold in stores everywhere (also under the name victoria green) and I even found it offered from some scientific supply companies. The main concern with it is that it readily bioaccumulates, and it was primarily banned for use with fish that are going to be consumed. I don't feel comfortable using it, and I don't want to explain why I did if I publish this.
In response to whether or not it is saprolegnia: I am pretty sure... I did the pathology myself, and it is not my strong suit. I know it is not as common, but it is fairly distinct under a scope. Either way, I will be bringing in fish to the state pathology lab tomorrow and they will be able to give me an accurate analysis. I will post those results on here as well since some of you guys may be interested what a Johnny Darter's background infection status is.
In response to collection: I will certainly try putting salt in our collection coolers. The water in that stretch of the S. Platte has very high conductivity, but it probably will not hurt. I am going to try to seine if I can, but chances are, I will have to shock (the chain suggestion may work wonders though!). I also appreciate you asking for any NANFA members to help out. I will have a whole crew from my funding agency helping out though.
Once again, I really appreciate the advice!
In response to the ammonium/nitrate/flow through system: By flow through system, I mean I have fresh water coming into the tanks and exiting out at approx. 800ml/minute (so it ends up replacing the water in the tank something like 12+ times per day). So there is no recycling of water. Therefore I am not really worried about nitrifying bacteria Erica was referring to or high ammonia or nitrate levels. I am waiting on ammonia and nitrate probes so I can check and make sure. That graph is quite interesting Erica! Thanks.
In response to the legality of malachite green: The law states that malachite green can no longer be applied to fish for consumption or non consumption. There has to be some loophole/grey area though because it is sold in stores everywhere (also under the name victoria green) and I even found it offered from some scientific supply companies. The main concern with it is that it readily bioaccumulates, and it was primarily banned for use with fish that are going to be consumed. I don't feel comfortable using it, and I don't want to explain why I did if I publish this.
In response to whether or not it is saprolegnia: I am pretty sure... I did the pathology myself, and it is not my strong suit. I know it is not as common, but it is fairly distinct under a scope. Either way, I will be bringing in fish to the state pathology lab tomorrow and they will be able to give me an accurate analysis. I will post those results on here as well since some of you guys may be interested what a Johnny Darter's background infection status is.
In response to collection: I will certainly try putting salt in our collection coolers. The water in that stretch of the S. Platte has very high conductivity, but it probably will not hurt. I am going to try to seine if I can, but chances are, I will have to shock (the chain suggestion may work wonders though!). I also appreciate you asking for any NANFA members to help out. I will have a whole crew from my funding agency helping out though.
Once again, I really appreciate the advice!
#18
Michael Wolfe
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Posted 25 October 2013 - 07:34 AM
If you dont mind talked a little bit more about your water... I am curious about this "flow through" that you are talking about... where does the water come from? where does it go to? are you getting water out of a river?
Either write something worth reading or do something worth writing. - Benjamin Franklin
#19
Guest_EricaLyons_*
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Posted 25 October 2013 - 11:48 AM
Is it chlorinated?
#20
Guest_UWYO_*
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Posted 25 October 2013 - 12:37 PM
Gladly. At our lab we have a natural spring that we pump water from directly into our head tanks tanks. In our head tanks we also add heated water (same source) to get the desired temperature (the spring water stays at 8-12 degrees C). None of it is chlorinated. Our Game and Fish Department as well as previous grad students before me have used it successfully with their fish (I do not know if they had any disease issues though). Anyways, from my head tanks, water is released into my splitter boxes which allows me to adjust the flow to the individual tanks. I keep the flow high in order to maintain temperature, and I also have insulated the tanks. If the temps get too high in the head tanks, I have an alarm system and emergency shut off to stop flow before the hot water gets to the fish. In each tank I have a glass stand pipe and the water drains from the tanks into drains that lead to a nearby lake (which is why I don't want to use malachite green), but first go through raceways with trout, aquatic inverts, and veg that act as biological monitors of our water. I have a lot of checks on the water. Additionally, my tanks are brand new, and I acid washed everything just in case. All the piping is either tygon, glass, or schedule 80 so there shouldn't be any heavy metal issues. Probably way more info than you were looking for, but there could be something I am missing here.
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