Why would fish die around day 30 in a new tank?

Lou Young · 02/13/2019, 07:51 AM

I have been breeding clownfish for fun for a few years now and never had this issue so I figured I would ask for some help. Starting at around day 30 the clownfish babies are dying slowly overnight. They are raised in a 10 gallon tank and I use a seeded sponge filter. Daily 2-3g water changes. I’d there anything happening in the nitrification cycle around the 30 day mark that would tend to kill small clownfish? Any advice is appreciated.
Thanks in advance?

dkeller_nc · 02/13/2019, 08:00 AM

I would not personally expect that you would see a problem with water chemistry around day 30 that wouldn't have manifested well before then. As I'm sure that you're aware, the typical issue in a tank with an insufficient bacterial filtration base is ammonia. And ammonia will typically start rising just a couple of days after putting inhabitants in a tank. By day 30, the cycling (whether intentional or otherwise) should be in the "nitrate" phase, with little to no ammonia or nitrite present, and nitrate generally isn't all that toxic to either freshwater or marine organisms unless the concentration is really extreme.

My guess would be that the clownfish are going through a metamorphosis phase around that time, and either something about the nutritional profile about the foods they've been fed up to that point are insufficient/inappropriate, or I suppose it's possible that the amount that the growing fish are being fed is overwhelming the aeration and/or biological filtration capacity of their tank.

The only way to know for sure is to test the tank's water. I would monitor the ammonia levels every couple of days, and the nitrate concentration every 4 or 5 days. Ideally, ammonia should always be undetectable, and nitrate should be <20 ppm, though I wouldn't suspect nitrate toxicity until nitrates were well over 50 ppm.

Lou Young · 02/13/2019, 08:13 AM

Thanks for the info dkeller. I appreciate it. I use Cloram-X along with daily water changes to keep ammonia pretty much at zero. I haven’t checked Nitrate or Nitrite levels though so I’ll do that. Normally by day 30 I would have moved them out of the 10g tank and into a grow out system with a skimmer and better filtration, but I took a break from breeding and need to start up the grow out system again. Thanks again.

Lou Young · 02/13/2019, 03:34 PM

Quote:

Originally Posted by dkeller_nc

I would not personally expect that you would see a problem with water chemistry around day 30 that wouldn't have manifested well before then. As I'm sure that you're aware, the typical issue in a tank with an insufficient bacterial filtration base is ammonia. And ammonia will typically start rising just a couple of days after putting inhabitants in a tank. By day 30, the cycling (whether intentional or otherwise) should be in the "nitrate" phase, with little to no ammonia or nitrite present, and nitrate generally isn't all that toxic to either freshwater or marine organisms unless the concentration is really extreme.

My guess would be that the clownfish are going through a metamorphosis phase around that time, and either something about the nutritional profile about the foods they've been fed up to that point are insufficient/inappropriate, or I suppose it's possible that the amount that the growing fish are being fed is overwhelming the aeration and/or biological filtration capacity of their tank.

The only way to know for sure is to test the tank's water. I would monitor the ammonia levels every couple of days, and the nitrate concentration every 4 or 5 days. Ideally, ammonia should always be undetectable, and nitrate should be <20 ppm, though I wouldn't suspect nitrate toxicity until nitrates were well over 50 ppm.

Alright. I did some water test.

Ammonia 0
Alk 4.2 DKH
Nitrate 10PPM
Nitrite 5PPM

outssider · 02/13/2019, 06:11 PM

You don't see alkalinity at 4.2 as a potential problem??? I have no idea if this is causing the death but it certainly can't be helping the situration...

dkeller_nc · 02/13/2019, 06:35 PM

This is honestly something that might be better answered by folks that regularly grow out clownfish, and might be able to give you some ideas about nutrition, particular stages in the metamorphosis that might be problematic, etc...

But from a water chemistry standpoint, I wouldn't expect that you have a problem. This article by Randy Holmes Farley quotes a study where flounder were exposed to a nitrite concentration of 46 ppm. There were some metabolic effects noted, but no mortalities. While a really low alkalinity might mean that you've a low pH, fish generally don't care about alkalinity in an of itself.

All of this, though, presumes that baby clownfish respond the same as other species and/or adult fish, and I just don't have enough experience with marine fish rearing to offer an authoritative opinion.

bertoni · 02/14/2019, 12:45 AM

I probably would work on the filtration level. Nitrite might not be toxic at that level, but I would expect a reasonable filter to keep that level towards zero. We are dealing with immature fish, so I'd be cautious.

Bananafish · 02/19/2019, 02:30 PM

When I was raising clowns, I had a 2-1/2 hatch tank. I moved them from there to a 10 gallon when they were almost 2 weeks old -- just in time to reset the hatch tank for more eggs. The 10 gallon was set up with dividers, and I'd have as many as 4 clutches of fish (that's over 300 babies) in the same 10 gallon tank. There is no magic 30-day die off. There is a high rate of die-off every day for 3 days, then at about a week and every few days until 2-1/2 or 3 weeks. Almost all the fry that made the 3 week cut-off eventually were sold when they were anywhere from 3 to 4 months old. I had very few fish die after the metamorphosis, and some of them were in there for a few months. You have something going on in that tank.

Your Alk is low. Should be closer to 7. And you shouldn't have nitrites. Those are probably the killer. You need to find out why you don't have good nitrite digestion -- and it may have to do with your daily water changes. Once they made the 10 gallon, my little critters got a weekly water change of about 2 gallons, and it came from the display tank -- no "fresh" water. You also might want to let the algae run wild in your grow-out tank. It will eat up all the nitrites and nitrates. The other thing that could be at play is osmotic shock. If you are topping off the grow-out tank with DI, you might be adding too much water at once. The little guys can't handle rapid changes in salinity. I used to solve this problem by setting up a small bottle of water and letting it drip into the back of the hang-on filter about once per second until the bottle was empty. I'd do a cup or two at a time to keep the level up and reduce the possibility of shock. I never put anything in the water. They only got DI to top off the tank or water from my display tank when they got a water change.

My avatar is from the last pic in my "Some Tank Pics" album. As you can see, my grow-out tank is chock full of algae. Two of the fish in that picture are the same two clowns in my "Reef 2.0 - Total Reboot" album. They will be 9 years old this June. I was raising clowns for about 3 or 4 years until Sandy wiped me out, and I have never seen anything like you describe in your original post.

FishAndPhysics · 02/22/2019, 01:07 PM

Are you dosing your water conditioner on the tank or the new water change water? IMO, adding water conditioner to your tank on a regular basis is a terrible idea. You are messing with the biological filter in odd ways by consuming it's food chemically. Add it to the water you are going to add salt to.

Lou Young · 02/24/2019, 01:46 PM

Thank you everyone for the comments. I believe I found the issue. Apparently I forgot to seed the sponge filters in the last few fish batches so there go. Brain fart on my end!!!!!

02/13/2019, 07:51 AM	#1
Lou Young Registered Member Join Date: May 2012 Posts: 410	Why would fish die around day 30 in a new tank? I have been breeding clownfish for fun for a few years now and never had this issue so I figured I would ask for some help. Starting at around day 30 the clownfish babies are dying slowly overnight. They are raised in a 10 gallon tank and I use a seeded sponge filter. Daily 2-3g water changes. I’d there anything happening in the nitrification cycle around the 30 day mark that would tend to kill small clownfish? Any advice is appreciated. Thanks in advance?

02/13/2019, 06:11 PM	#5
outssider Registered Member Join Date: Nov 2009 Location: Reseda, Ca. Posts: 1,717	You don't see alkalinity at 4.2 as a potential problem??? I have no idea if this is causing the death but it certainly can't be helping the situration... __________________ Please don't feed the bears because the bears will become dependent on free handouts and forget how to take care of themselves …... Current Tank Info: 75 Gal. Mixed reef mostly sps

02/14/2019, 12:45 AM	#7
bertoni RC Mod Join Date: Mar 2002 Location: Mountain View, CA, USA Posts: 88,616	I probably would work on the filtration level. Nitrite might not be toxic at that level, but I would expect a reasonable filter to keep that level towards zero. We are dealing with immature fish, so I'd be cautious. __________________ Jonathan Bertoni

02/19/2019, 02:30 PM	#8
Bananafish Registered Member Join Date: Jan 2011 Location: Western Suffolk, New York Posts: 311	When I was raising clowns, I had a 2-1/2 hatch tank. I moved them from there to a 10 gallon when they were almost 2 weeks old -- just in time to reset the hatch tank for more eggs. The 10 gallon was set up with dividers, and I'd have as many as 4 clutches of fish (that's over 300 babies) in the same 10 gallon tank. There is no magic 30-day die off. There is a high rate of die-off every day for 3 days, then at about a week and every few days until 2-1/2 or 3 weeks. Almost all the fry that made the 3 week cut-off eventually were sold when they were anywhere from 3 to 4 months old. I had very few fish die after the metamorphosis, and some of them were in there for a few months. You have something going on in that tank. Your Alk is low. Should be closer to 7. And you shouldn't have nitrites. Those are probably the killer. You need to find out why you don't have good nitrite digestion -- and it may have to do with your daily water changes. Once they made the 10 gallon, my little critters got a weekly water change of about 2 gallons, and it came from the display tank -- no "fresh" water. You also might want to let the algae run wild in your grow-out tank. It will eat up all the nitrites and nitrates. The other thing that could be at play is osmotic shock. If you are topping off the grow-out tank with DI, you might be adding too much water at once. The little guys can't handle rapid changes in salinity. I used to solve this problem by setting up a small bottle of water and letting it drip into the back of the hang-on filter about once per second until the bottle was empty. I'd do a cup or two at a time to keep the level up and reduce the possibility of shock. I never put anything in the water. They only got DI to top off the tank or water from my display tank when they got a water change. My avatar is from the last pic in my "Some Tank Pics" album. As you can see, my grow-out tank is chock full of algae. Two of the fish in that picture are the same two clowns in my "Reef 2.0 - Total Reboot" album. They will be 9 years old this June. I was raising clowns for about 3 or 4 years until Sandy wiped me out, and I have never seen anything like you describe in your original post. __________________ ~ Sal ~ Current Tank Info: It's 3,000 gallons smaller than I wish it could be

02/22/2019, 01:07 PM	#9
FishAndPhysics Registered Member Join Date: Jan 2016 Location: NY Posts: 95	Are you dosing your water conditioner on the tank or the new water change water? IMO, adding water conditioner to your tank on a regular basis is a terrible idea. You are messing with the biological filter in odd ways by consuming it's food chemically. Add it to the water you are going to add salt to. __________________ 90 Gallon Mixed Reef with 20g sump Current Stock: 1 - Ocellaris Clownfish, 1 - Yellow Tang, 1 - Kole Yellow Eye Tang, 1 - unidentified hitchhiker goby, 1 - Coral Beauty, 3 - Lyretail Anthias.

02/13/2019, 08:00 AM	#2
dkeller_nc Registered Member Join Date: Mar 2013 Location: Central NC Posts: 5,062	I would not personally expect that you would see a problem with water chemistry around day 30 that wouldn't have manifested well before then. As I'm sure that you're aware, the typical issue in a tank with an insufficient bacterial filtration base is ammonia. And ammonia will typically start rising just a couple of days after putting inhabitants in a tank. By day 30, the cycling (whether intentional or otherwise) should be in the "nitrate" phase, with little to no ammonia or nitrite present, and nitrate generally isn't all that toxic to either freshwater or marine organisms unless the concentration is really extreme. My guess would be that the clownfish are going through a metamorphosis phase around that time, and either something about the nutritional profile about the foods they've been fed up to that point are insufficient/inappropriate, or I suppose it's possible that the amount that the growing fish are being fed is overwhelming the aeration and/or biological filtration capacity of their tank. The only way to know for sure is to test the tank's water. I would monitor the ammonia levels every couple of days, and the nitrate concentration every 4 or 5 days. Ideally, ammonia should always be undetectable, and nitrate should be <20 ppm, though I wouldn't suspect nitrate toxicity until nitrates were well over 50 ppm.

02/13/2019, 08:13 AM	#3
Lou Young Registered Member Join Date: May 2012 Posts: 410	Thanks for the info dkeller. I appreciate it. I use Cloram-X along with daily water changes to keep ammonia pretty much at zero. I haven’t checked Nitrate or Nitrite levels though so I’ll do that. Normally by day 30 I would have moved them out of the 10g tank and into a grow out system with a skimmer and better filtration, but I took a break from breeding and need to start up the grow out system again. Thanks again.

02/13/2019, 06:35 PM	#6
dkeller_nc Registered Member Join Date: Mar 2013 Location: Central NC Posts: 5,062	This is honestly something that might be better answered by folks that regularly grow out clownfish, and might be able to give you some ideas about nutrition, particular stages in the metamorphosis that might be problematic, etc... But from a water chemistry standpoint, I wouldn't expect that you have a problem. This article by Randy Holmes Farley quotes a study where flounder were exposed to a nitrite concentration of 46 ppm. There were some metabolic effects noted, but no mortalities. While a really low alkalinity might mean that you've a low pH, fish generally don't care about alkalinity in an of itself. All of this, though, presumes that baby clownfish respond the same as other species and/or adult fish, and I just don't have enough experience with marine fish rearing to offer an authoritative opinion.

02/24/2019, 01:46 PM	#10
Lou Young Registered Member Join Date: May 2012 Posts: 410	Thank you everyone for the comments. I believe I found the issue. Apparently I forgot to seed the sponge filters in the last few fish batches so there go. Brain fart on my end!!!!!