Pond Boss Forums INTRO Questions & Observations concrete tanks

BLusk in his thread mentions using concrete tanks for holding fish. My question is-are concrete tanks (or specifically, septic tanks) acceptable for raising fish? Is there a treatment to concrete step before introducing fish? thankyou

I'm of the opinion that just plain concrete is pretty innocuous. Is there any kind of coating that they put on concrete septic tanks? If not, I'd wash the tank out good and give it a go.

Of course, the first time I used it, while I was learning, I'd be using cheap, easily replaceable or surplus fish.

The only downside I can see from the concrete tanks, is possibly high PH levels.

In my neighborhood a concrete slab is poured, then concrete blocks are used for the sides. Concrete is used instead of plaster. They are generally small, 8' by 10'. The bottom is covered with dirt, water is added and allowed to sit for two weeks until the proper bacteria is formed at which time the fish are added. They may or may not add plants. The neighbor nearest me has ten of them, two rows of 5 each. Her's are fitted with drains and overflows for the rain and she keeps them topped up with well water. Some here are used for aquaculture, a truck comes by and sells you umpteen baby cats and returns in 4 months and harvests them, you are paid by th kilo. The majority are for personnal use to raise food. The only washing the tanks received is from the rain. The algae bloom here can be awesome, but the cats seem to survive.

Rad, what species are the cats? Is there any way you can get some pics of the tanks and the cats? What do they feed the cats? Do they have a high mortality rate? There's not a whole lot that you post about that I don't find interesting or maybe even fascinating.

Mekong cats - 600 hundred lbs. - one to a tank. you can practice bull riding on them -- $5 per min. - but don't fall off as you might become dinner.

Dave,
I will try to get a picture or the personal use and another of the aquaculture in the next couple of days. I didn't ask about the mortality rate, but the several times I have seen both of these tanks I have never seen a dead fish. The feed depends on the budget, 15% pellets are the mainstay supplemented by leftover vegetables. The species might but difficult, many of my neighbors get their fish from rice paddy ponds, the aquaculture people buy from the cheapest source. That is the main reason I have shied away from cats, you never know what ou are getting. Here catfish is a generic term with snakeheads lumped in.

What does this mean? I'm a little bit slow.

To cover the blocks on the tank sides, I'm guessing.

This is a very confusing night for me. Why don't the concrete block just fall over from the weight of the water? Would you pour the concrete into the holes of the concrete blocks?

I remember reading somewhere that one problem with concrete tanks is the rough texture of the concrete which can cause abrasions on the fish (specifically the eyes). This is generally more of a problem in aquaculture when the fish densities are high.

That makes a lot of sense. In my plastic tanks the surface is so smooth that it's easy to disturb the algae growth when I'm draining the tank so it goes down the drain. It would seem that it would be more difficult with a rough, irregular surface.

Right Theo, most of the buildings in my neighborhood are constructed using concrete blocks. We lay them using a concrete mix as the mortar and to cover the surfaces, this covering concrete is what provides most the strength to the walls. The blocks here are 3" wide and the concrete varies depending on the skill and budget of the applier. The smoothness of the surface is also determined by the same factors. An extremely smooth surface is not difficult if a skilled finisher is used. The tanks are not filled with much water. I will try to get out and take a few pictures today. Bruce, you are not slow, remember, this is just foreign to you.
Dave, I was at the farmers market yesterday and one of the vendors had two baskets of fish for sale, when asked, both were catfish, I remarked that they did not look the same and she told me they were all Catfish. I know one was a snakehead. So I guess it is up to the buyer to know. I will try to locate the fish names on my Thai fish chart.

Amazing how much work I get done when you guys are asleep.
The tanks are about 3' high and have about 1' of water. I think she told me there were 200 fish in each tank, she stocks her tanks in two week intervals. There is always a tank that is 2 weeks in waiting while the bacteria develops. She begins harvesting the first tank at 4 months, the next tank two weeks after that and so on.

It took her awhile to learn that buying good stock and good food was a real money saver. Her father almost had a stroke when she told him what she paid for a bag of food. Her father never paid to feed anything in his life, including her.

But, he got his comeuppance when she sold her first batch for more money than he makes with his fish in a year. She nets between $250 to $300 a tank. I think I will skip the picture of the other type of tank, it is very much like these in construction, it is just a single and is covered with palm fronds instead of shade cloth.
Dave,
I checked my Southeast Asia Freshwater Fish chart and could not find either the catfish or snakehead that is grown and sold locally. It may just be that the fish I see are all black because of the water, blue-green algae bloom, in which they were raised, I am not sure. I looked at them in the market yesterday and they were too black to see much detail, none of the fish on the chart are black. Sorry, maybe that is why they are all simply called catfish?

rad, thanx great pictures, they dont really grow mekong cats to 600# in 4 months tho, do they? those would probly have to be radient heat lined concrete tanks way up here to get that kinda growth.

BC, so will those smooth plastic tanks float out of the ground?

so if the concrete tanks are high ph a ocntinous flush thru tank = no worries. and i am not sure that is accurate

ok, here is a link found on a google search for high ph concrete tank

http://govdocs.aquake.org/cgi/reprint/2003/1201/12010030.pdf

golden arawana, i saw that fish in sumatra in glass aquarium in guest house, it attacked me, there was one at airport in jakarta. does anyone have any other links to that fish? or am i hijacking my own thread?