Catfish deaths?

[David Morse]

I started raising catfish and goldfish in my system back in August.  I started with just two catfish and three goldfish.  I have two 55 gallon drums, so I split the fish up.  The system feeds one 55 gallon drum of grow medium.  The grow bed drum is cut in half long ways.

 

The cats grew to about 8 - 10 inches, so I added five more in January thinking things were stable.  In the past month I've lost all 7 cats, but not a single goldfish.  I did some basic water test and nothing seemed out of order. I think the catfish were called blue catfish not the channel catfish I see most people growing. 

 

Any ideas on what to test before I try more catfish?

[TCLynx]

Were there any signs of illness in the fish before they died?  Catfish can be very prone to collumnaris disease which can present in white patches on the skin (saddle back) and proceed to the skin basically rotting off and showing the flesh under.  It can also infect the gills or skin around the mouth and eyes.  This is a bacteria that is really very common in the water and likely present all the time but when water quality is kept very high and the fish are not stressed, the fish tend not to get sick.  However, it does commonly flair in the spring as feeding is increased but the water temps are still not too high.  Even brief spikes in ammonia can greatly stress catfish making them suseptable to disease and by the time the fish are sick the water quality spike may be long gone.  I lost many catfish this past winter/spring probably due to one overfeeding incident and subsequent handling.

 

I have also never managed to keep catfish bigger than about 6-8 inches healthy long term in a smaller tank.  Even a 100 gallon stock tank was not big enough in my opinion for my channel catfish beyond the initial quarantine of the 3-5 inch fingerlings.  When I put a dozen 6-7" catfish into that same 100 gallon stock tank, they were plagued with skin issues and I lost a few until I moved them out of that tank.  I will no longer grow out channel catfish in anything smaller than 300 gallons and I like at least 24-30 inches of depth on the water for channel catfish as well.

 

I know you are growing blues rather than channel catfish but they are very similar fish.  I think your problem is a 55 gallon drum is too small to grow out catfish bigger than about 8 inches at least in my opinion.  A fish bigger than 8-10 inches is going to be rather restricted in a tank that is only 24 inches across.  Now I know there is a book out there some where that said you can raise catfish in a 55 gallon drum but there are people who happily eat catfish that are only 8 inches long.

 

Seeing as you have 2 55 gallon fish tanks and only 55 gallons of grow bed.  You do not have enough filtration to be upping the fish load much.  By my estimation with only about 50 gallons of grow bed happening, I would only recommend about 6 fish.  (Recommending 1 fish per cubic foot of flood and drain grow bed media, a cubic foot being about 7.5 gallons so 50 gallons divide by 7.5 = 6.6 so adding 5 more fish back in January set you up to push the limits of your filtration and I expect as things started to heat up and you started to feed more, you may have had a little spike in your water quality that stressed your catfish a bit and opened them up to illness.  This is just a theory, handling of catfish also opens them up to illness.  And since catfish tend to pile up on each other in a tank, illness can spread quickly among them.

 

Make sure solids are not building up in your tanks anywhere and clean out any uneaten feed or fish poo that has been collecting.  Before adding new fish I would salt the system to about 3 ppt of salt.  Be sure to dissolve the salt completely before adding into the system since salt crystals sitting on the bottom of a fish tank will burn fish that rest against them.  I usually use the cheap pool salt or water softener salt but make sure what ever salt you use in non-iodized and doesn't have anti caking agents (table salt) or pelletizing agents (water softener pellets.)  I would recommend larger tanks and more grow beds for growing out catfish though.

[David Morse]

Thanks.  You've mentioned a couple possible issues I had after adding the extra fish, so I'll take more caution or maybe switch to another type of fish as my goal was to grow a few fish for food.  It sounds like the 55 gallon drum is not suitable for growing larger catfish.

 

I keep my water temp at a constant 73, but I did have food build up back in February when I had someone else maintaining the system during my vacation.

 

Do yo think with less they'll produce enough food for the plants?  I get the feeling my plants are nutrient deprived as they tend to grow on the leggy side.

 

I'm not familiar with salting the system, what is the 'ppt' measurement?

 

Thanks for the help.

[TCLynx]

leggy plants is usually more a lack of light and/or trace elements.  Once a media based system is cycled up and mature, you really don't need many fish to provide nutrients.  Sign of not enough fish would be a 0 nitrate reading along with the plants lower/older leaves turning yellow.  If you have plants yellowing but there is still any nitrate in the water then it's probably some other deficiency and not a lack of fish.

 

ppt stands for Parts per thousand.  Here is a blog post with some numbers for figuring out the right amounts of salt to use.

Salt For Fish Health

 

You don't want to add salt often, only when adding new fish, dealing with nitrite spike, or experiencing fish illness.  Catfish can't take much salt so I never go above about 3 ppt with them.  Salt can do in strawberries.

[David Morse]

I did a through cleaning of the two tanks and added a little salt as suggested.  I happy to report my two cat fish are still alive and seem to be more active and eating better.  Thanks for the advice.

[TCLynx]

Good to hear.