Monday, June 29, 2015

The need for predators in tilapia farming



For some this may make no sense as to why one would want something to eat their fish, if they are trying to grow and raise them. I felt exactly the same way at first.

When you purchase your tilapia, the majority, and I am talking about 98-99% here will be male. The reason for this is they are given a hormone at the start of their life which can alter their sex. 1-2% doesn't seem like a lot of females but when you realize the amount of eggs a female can produce, and many of those will be females. you can see how the problem can escalate.

There are several reasons why you don't want breeding to occur. The first is you will have a population explosion. These fish will all be competing for food. As such none will grow to the intended size you had hoped for.

The second problem will be as the fish are breeding, they make holes (nests) along the edge and bottom. This will result in an uneven bottom making netting much more difficult. When the time comes to net the lake, the fish will be able to escape below the net using one of these holes.

Another problem which we were unaware of at first was the behavior of the fish. We netted some larger fish and put them in our tanks waiting for them to sell the following weekend. It was here where we saw behavior which would also be occurring in the lake, although unseen.

In tanks with a female, she would stay in a corner guarded by a male. The other fish would hover around waiting for their chance to be 'top male'. They were so interested in her, they weren't eating. Tilapia which aren't eating aren't gaining weight and aren't going to earn you money.

It is for the above reasons why you need predators if you have your fish swimming freely and don't sell all of them before breeding begins, which can be as early as 4 months

Tuesday, June 23, 2015

Fish theft on our tilapia farm




In this post I would like to discuss something which many people don't consider before entering fish farming. That is the potential of theft of your fish. Just as people steal herds of cows so too can they steal fish. I touched on this subject in an earlier blog post and today, I would like to tell you about our experience with it and what we have done to rectify this problem.

It is easy to think that fish won't be stolen, after all they have a very short life outside of the water, unlike land based animals. It still occurs and because the fish are out of your view, if they are in a lake or in cages in a lake, you won't know they have been stolen until it is time to harvest and your numbers, are way down. In that sense it is a perfect crime waiting to happen because the owner may not even know if there are fish missing.

We only discovered we were being robbed when the thief left his flip flops behind. Here in Brazil everyone wears Havaianas (a popular brand of flip flops). My husband brought these back to the house and said, “you left your flip flops out by the lake.”
To this I replied, “those aren't mine!”

It was at that point we knew someone had been in here at night. When we looked at where my husband found the sandals we could see drag marks across the grass to the corner of our property. The thief had filled bags full of fish and dragged them to his bicycle which was waiting in the shadows of the road.

We telephoned the police and they arrived but of course there was nothing they could do. They did tell us that what we do on our property to secure it and our business is down to us. (within reason of course)
We have dogs but we found that the thief had been feeding the dog which was loose at the time to keep it quiet. We saw margarine tubs and bags. Because people in this area burn their own trash, we had assumed these had blown in. We were wrong.

When I look back now at how easy we made it for someone to steal our fish, I am angry with myself as well as the thief.

Our lake was surrounded by tall reeds making this an ideal hiding place. We also had long grass growing near our fence which obscured our vision of the property line. 


We knew that the fish would have to be sold the following morning and knew that it would be a Thursday or Friday night the thief would return.

My husband cut down the long grass near the fence. Cutting the reeds was going to be a mammoth task so in the short time we had (one week) we decided to place broken glass in the area he had walked in and out of the lake. This is something which many of the walls have cemented across the tops to prevent someone climbing over them.

Wearing camouflage clothing my husband waited up on the outside terrace for him to return. If he came in, again he wasn't going to be leaving in the same condition. Armed with a piece of hardwood the length of a baseball bat, my husband watched and waited. I joined him on the front terrace sitting in the dark waiting. Just before 1am we saw a bicycle approach. We are the last house on our dead end lane and anyone who is there, shouldn't be. Because our eyes had adjusted to the darkness we could see him moving in the shadows. This was about 150meters away.
I don't mind telling you my heart was beating like crazy and my palms were sweating. My husband is in his mid 60s and an amputee but he had already worked out his route to approach him from behind. This thief wasn't going to be leaving without some serious damage. First was going to be the knee caps, the head, and then the body. He was going to be made an example of!

If this sounds extreme, wait until you are put in this position. We are not like the typical foreigners who come to Brazil. Most have full time housekeepers, and gardeners. We have neither and we work harder than anyone I know.
Here in rural Brazil, there is an uneducated percentage of the population which thinks if you are a foreigner, you are rich and it is okay to steal from you. The anger I still feel about this incident, although several years has passed, is still there. I would have had no qualms seeing my husband inflict repeated blows to this man.

Because we had cut the grass near the fence, I believe the thief knew we were on to him and rode away.

Making changes
Fencing:
We have made some changes since that incident including improvements to the fence. We have several runs of barbed wire on reinforced concrete. This is okay until someone brings a pair of pliers and cuts the wire. Still it is a visual reminder.

Better watchdogs. Although we had two mutts we added to this with a Brazilian mastiff. These dogs, although gentle with their owners can bring a man down with their sheer size. The downside with dogs is people here poison them by throwing tainted meat over the fence. This is what I have been told although it has never happened to us.Here in Brazil, as long as you have a sign up warning people you have a dog, you face no problems if your dog injures or kills someone who enters without your permission.

Better lighting around the property. Thieves like the cover of darkness. Adding lights also helps neighbors and their dogs to keep a watch out for people on your property.

Cutting of the reeds. This was a huge job and we did hire someone in to help us. Although we love to see the reeds and enjoy the privacy they provide, they allowed the thief to hide in them.


Obstructions:At the time we had fish in cages and in swimming free in the lake. To ensure no fishing with a net could take place we submerged large tree branches. This would snag any net being used.

Better cage security:We also securely tied the tops of the cages down. It has been known that some thieves will cut the plastic below the water line and put a bag over the opening. The fish swim out of the cage and into the bag.

We also changed the lights in the house and put some on a timer switch. If someone thought people were still awake, they would be less likely to enter. 

We have not had a problem since this occured.
 I have read that in some areas of the Far East they will have someone sleep on a platform near the fish cages to prevent theft. 
I am aware of large shrimp farms near here which hire armed guards to protect their livestock. There are always options available which need to be weighed up which is best for your situation.

Monday, June 15, 2015

The cost of electricity




For many people this could be the making or breaking of a profitable tilapia business. The cost of your electricity is something which needs to be taken into consideration before embarking into the fish business.
The electricity usage would come from a few different avenues.
  • Aeration
  • heating of water
  • water pumps
  • security lighting


The aeration, if you are using, can be costly and this would have to be weighed off against the increase in the number of fish you can rear with using it. Some people we know only used their aeration systems over night. We used ours 24/7.


The heating of the water is something you may have to consider depending on where you live. This isn't always necessary as tilapia are hardy fish and can take temperatures as low as 45ºF (7ºC). Although that means your fish might survive it doesn't mean they will thrive. Remember you are in this business to make money and that means you want to spend as little as possible to make maximum profit. If your fish are using their energy (provided by the food you are feeding them) to keep warm, they aren't using those calories to grow.

Water which is naturally warmed by the sun is best for your pocket.
This is one of the reasons why Brazil, where I live, is perfect for raising tilapia, we never have to heat the water.

In saying that, if we were pumping straight out of the ground into tanks, it is cooler and would affect production and profitability.

That brings me to the next item on the list. If you are moving water from one lake to another or continually adding fresh water you will be using some sort of pump. There are many types available. To know which is best for your set up, it is worth speaking to an adviser who sells them. They will be able to tell you the volume of water each pump can move through the various pipes. This is also dependent on the depth of your well. 
 


Security lighting around your farm is necessary. You have a valuable and easily removable crop and lights are necessary. There is also the added benefit that these lights attract insects which fall into the water. An additional ( and free) protein source for your fish. 

Monday, June 8, 2015

Cages for fish rearing

Here on our tilapia farm we have three different types of cages. There are several materials which you can use to make the structure with and also those which form the netting of the cage itself. You can buy them ready made on places such as Ebay or you can make them yourself.

We bought ours used, and did a few repairs to them to get them ready for the fish.

Our cages which are 3m x 2m are on aluminum frames and the cage itself is plastic coated wire. This has advantages and disadvantages. The advantage is it is lightweight. When you are moving or lifting it , once filled with fish any extra weight just makes your job more difficult.
The metal cages could take fish beginning at 50grams, any smaller and they could swim out through the space between the chainlink.


tilapia cage

The other type we have is heavy duty plastic on a wooden frame. These are 2m x2m and are heavy.This is due mainly to the frame as all the wood here in Brazil is hardwood. Yes the wood will last virtually forever but it is heavy. The plastic netting is very strong and the gaps are smaller which allowed us to buy smaller (less expensive) fish. When using the plastic cages, we could buy fish which were 30grams.

The third type which we bought, we didn't use as, although it was lightweight, it was cumbersome. This was made out of pvc pipe and was rigid.

The truth is you can make the size you want or need using most anything.
The 3m x2m has the capacity to hold 900 fish and the 2m x2m can hold 600. We always kept the amount less than this as we didn't want to stress the fish.

To keep it afloat we had a welder make small baskets into which we put empty plastic bottles. These had originally held industrial cleaning products but once empty were sold off for various uses. If you use this idea, be aware that after a time in the sun, the plastic does become brittle. It is always a good idea to have spares around, otherwise your fish could escape as the cage would sink on the side where your container has filled with water.

It is also necessary to have a lid on your cage for a couple reasons.
  1. Fish can jump out.
  2. To keep fish eating birds out. This includes herons, egrets, cormorants etc
  3. To keep birds from eating the fish food.

Along the top edge of the cage you will also need to put a fine mesh. This should be tied down to the cage. This keeps the fish food from floating out before the fish eat it. 

Sometimes you may notice the tilapia have red or bleeding mouths when raised in a cage. This is from hitting the side of the cage, trying to get out. This however never affected resale value as we sold by the kilo. 

Monday, June 1, 2015

How to build duckweed ponds

Here on our farm we built 5 duckweed ponds after reading about this fabulous plant. We had not seen this plant growing locally but luckily a friend of ours, found some in a pond in the mountains near here. He brought us two types, on with smaller leaves and one with larger. He was studing botany and told us the smaller leaf variety did better in a shady spot and he was right as our ponds were in the full glare of the sun and it was the larger leafed variety which grew well in our conditions.
View across duckweed ponds

We hired a backhoe and a driver to dig our lakes which were 30 m long by 2 m wide (98' x 6.5'). We then put clay down and lined them with a plastic liner. These are shallow, only about 2' deep.
Clay lined duckweed pond



 As you can see these take a bit of organising but in the end, they aren't that difficult to create. If you were to build them there are a few things to keep in mind.
The liner is crucial. Here we had to take several things into consideration.
  • Ability to cope in extreme UV conditions. (we have over 300 days of sun a year and more often than not our level of UV (Ultraviolet light) is in the extreme category. Your local weather forecast can help you determine what your UV index is for your area. 
  • Non-leaching. We had to make sure that no toxic or unpleasant chemicals would leach into the water which could cause problems for the duckweed and subsequently the fish.
  • Robust. We had to have a strong plastic liner. Often bits of twigs might end up in there. Also we have chickens. We needed something that was tough enough to resist being damaged.
Various stage of completion
We first lined ours with clay as you can see in the pictures. This was delivered and we spread it manually and flattened it down to prevent any pebbles from damaging the liner. The reason we used clay is if any water were to seep out from the liner, it would be a slow leak. We have sandy soil here and it sucks up water better than a sponge, hence our need for clay.
Overflow system for duckweed ponds
Because this was only designed by us, we had to solve problems as we went. What you see pictured above is the ingenious (and cheap) solution my husband came up with. The problem was, we needed an overflow system for water to run out if the ponds got too full. We can get heavy downpours in our wet season which would have sent our duckweed up and over the edge in a rainstorm. We could have lost it all if that happened. Remember, duckweed is a floating plant, it isn't rooted into anything.

My husband place plastic pipes from one lake to the other. Then to keep the duckweed in and allow the water to flow out, he simply cut the bottom off a 2 liter soft drink bottle and insert this onto the plastic pipe. The excess water would escape and the duckweed would stay in the pond.  Sometimes the solutions to problems are easier than we think.

We started these ponds with just a few duckweed plants and yet you can see how quickly and how full they became. It can double itself in about 16 hours!


Feeding your Duckweed Pond
You will need to help your duckweed to grow by adding manure. We used chicken manure which a friend of ours sells. He buys it in from a factory farm and it is extemely strong. My husband would half fill a plastic trash can with manure and add water to soften it. This he would then throw into the duckweed ponds with a bucket. This ensured it was spread throughout the pond. If you have put enough manure in, you will see a growth spurt. If you don't, look at the roots of the duckweed plant to see how long they are. If they are long, perhaps more than 2 inches, you need more manure. Duckweed loves mucky water. Infact there are countries, Palestine for example, which use duckweed to clean their water supply. It is one plant which has so many uses. For more information about some of the other uses, I have written another article on Hubpages.
 http://blond-logic.hubpages.com/hub/duckweed

Cleaning your duckweed pond

I know what you are thinking, that this is going to be difficult but it isn't and it is necessary from time to time. If your duckweed seems to be slowing down with its reproduction it might be time to change the water and start again. We had to do this when we had a build up of sawdust in our ponds. This came in with the manure as this is what was used on the floor where the chickens were kept.
There are a couple of ways to do this, either let the water evaporate or drain it with a bilge pump, or a siphon. If you are going to be siphoning this, using your mouth to start the flow of water, remember how much manure you have been putting in there.

Remember keep some duckweed as a starter  

This starter can be kept alive in water until your pond is ready to go again. Once dry, sweep and remove any twigs, leaves or other debris from your pond. This is a good time to inspect your liner below the water line.

Havesting your duckweed

Harvesting is easy. We used a swimming pool net on an extendable aluminum pole. We briefly let the water drain from the net and then turned the duckweed into a large plastic box. We filled this full. This was then loaded onto our kayak  to take to the tilapia which we had transfered to cages.
Because we were harvesting every other day we were able to check the liner for any problems above the water line as a matter of course. A quick once over as we were scooping it out meant any problems were dealt with early and were thus easier to control.

Cost vs Savings

The cost for us was perhaps more than it would be for yourselves as we had to hire a machine to dig the holes for us. But compare this to the savings. If you calculate that your fish are only eating commercial fish food every other day, you have halved your food bill. If you only have a small number of fish, maybe this isn't commercially viable. We had bought 10,000 and had it definitely made financial sense to do this.
We produce healthy, weighty fish at half the cost of other fish farmers in this area.