Sometimes it’s nice to have a canary…

[Magnum Man]

I have mosquito fish in the plant tank of my Tilapia set up… last couple days they have been acting strangely, found one dead today… tilapia are getting big, I’m a couple weeks away from starting them on the finishing pellets ( that means they are almost all 6 inches or so ) the bio load has crept up… Tilapia can handle that, but I’m not wanting them to have to, so I had just done about a 20% water change yesterday, upon finding a dead mosquito fish today, I tested the water..nitrates, and nitrite’s tested high, so I did another 33% water change just now… like a canary in a coal mine… the mosquito fish are letting me know something needs attention, before the Tilapia have an issue…

 

[CaptainBarnicles]

I've never grown fish like you are doing but I'm assuming the bio load in those big tubs would be difficult to keep on top of without big water changes was the 20% sufficient?

 

[Magnum Man]

Apparently not… it was enough to keep the Tilapia alive, but I did an additional 33% change ( 250 gallons ) today, then an additional 50 gallons after that today… nice that the set up is outside, yes I like to add fish water to specific plants, but I can just syphon the water out to water the lawn… looks like I’ll be doing at least a 33% water change every week, and a lot more water testing weekly

 

[Colin_T]

Small water changes are useless for diluting things.

If you do a 30% water change each week you leave behind 70% of the bad stuff in the water.
If you do a 50% water change each week you leave behind 50% of the bad stuff in the water.
If you do a 75% water change each week you leave behind 25% of the bad stuff in the water.

 

[GaryE]

My daughter has a canary, and while its main thing is singing, I guess it could warn her if an unknown coal mine in the basement went toxic. But Gambusia... I can't imagine how a Gambusia would sing. I don't think it would be pretty.

I think with food fish Tilapia in containers, even big ones, you are going to work hard for every filet.

 

[Uberhoust]

Your comments made me think back to some of the catfish farms I saw when doing work in the Southern Eastern US. While working down there I kept seeing what I thought were sewage pond aerators in the middle of big muddy ponds. I was told these were aerators for catfish farms. I looked up how they dealt with nitrites in those systems and found some information from the Southern Regional Aquaculture center. The data is old but might help you. The link is to a PDF you have to download. Search was "catfish farming, how to deal with Nitrite" https://www.bing.com/ck/a?!&&p=5948...zdXJhbmNlJTIwYnVmZmVyJTIwYXMlMjB3ZWxsLg&ntb=1

 

[Magnum Man]

Wow... I found that very interesting & informative... thanks

I may have been accidentally, at least partially, taking care of this, as I have a whole house softener, that is an ion exchange unit, so there is already a base sodium chloride level in my water ( that has been causing a lot of problems in my aquariums... so I have recently installed an RO unit for my aquariums ) Tilapia are able to handle the salt, in fact, they are supposed to be very good at handling hyper-salinity, so I have not been as worried about them with my whole house softened water...

this week I'll be adding adaptors to the drain valves on the tanks, & be able to do major water changes as needed, verified by monitoring...,

not sure if the high heat index had effected anything, but we had 120 degree heat index last week, on one day, with over 100 for 4-5 days in a row... but I have been able to maintain my target tank temperature of 87 - 88 degrees, by placement ( they are in partial sun / shade ) & the introduction of fresh water... I've not witnessed surface breathing, since I added the air stones, but I'm definitely on a short growing season, so I'm feeding at maximum ( I even added the overhead grow lights to extend active fish hours, an hour earlier & later than daylight a month ago, & I get 2 additional feedings per day )