qestion

[kaveh arabdashti]

Hi,

 

Is there any table or guideline for 

1) calculation of standard(or normally expected) growth rate of trout/rainbow fish for breeding in raceway base up on feeding rate , temperature of water and another measurable factors , which we can compare or actual performance with these baselines?I found some material in internet(attached) , but they are too complicated and I think it is suitable for university doctors only!

2)Length-weight relationship during different stages of trout/rainbow fish growth? I found one text in internet (attached), but it cover only temperature between 4 up to 15 centigrade and does not cover temperature between 16 up to 23 centigrade and it is old and may be out of date,  

3)maximum permitted biomass of trout/rainbow fish in specific volume of raceway water ? 

 

 

 

Best regards

kaveh

[Vlad Jovanovic]

You should find and use such a published table from the manufacturer of your feed, use it as a guide then adjust that to conditions at your farm.

The reason those links do not list growth rates at higher temperatures is probably because at water temperatures above 22°C, a trout's digestive system becomes inefficient and much of the nutrient content of the feed ends up as waste in the water. Optimum growth for trout occurs between 12-16°C. When water temperature exceeds 20°C, feeding time, feeding frequency and amount of food per feeding should be adjusted based on dissolved oxygen levels. 

At 4 Celsius and below, their appetites may be suppressed and their digestive systems operate very slowly. Trout will require only a “maintenance” diet (0.5 percent to 1.8 percent body weight/day, depending upon fish size) at these temperatures... more than this will result in poor food conversion and wasted feed...

The maximum amount of bio-mass that can be held in a rearing unit (tank, raceway or pond) is referred to as carrying capacity, or stocking density  The actual carrying capacity of a culture unit depends on water flow rate, water volume, water temperature, dissolved oxygen concentration, pH and fish size, and in the case of AP, bio-filtration would be among your main concerns as well. 

Carrying capacity in much trout raceway literature is expressed in terms of weight of fish per unit water volume (kg fish per cu.m.) or in terms of weight of fish per unit water flow (kg fish per liter of water per minute). A common method for estimating maximum carrying capacity in a tank or raceway is the Density Index (D). The Density Index is a factor which, when multiplied by rearing unit volume in cubic feet (V) and by fish length in inches (L) will give the maximum allowable weight of fish (W): W = D x V x L As a rule of thumb, D for trout should be from 0.4 to 1. In other words, fish densities (pounds of fish per cubic foot of tank space) should be no greater than 0.5 to 1 times their length in inches. For example, if a D factor of 0.5 is used, 2- inch fish could be held at a density of 1 pound per cubic foot (0.5 x 2). If a D factor of 1 is used, 2-inch fish could be held at a density of 2 pounds per cubic foot (1x2).

While the D is useful in estimating carrying capacity, it considers only space (pounds of fish per unit volume). Another very important consideration in establishing carrying capacity is flow rate. The flow rate determines how rapidly fresh water will replace "used" water (water in which fish have reduced dissolved oxygen concentrations and excreted waste products). So your bio-filtration capacity and dissolved oxygen (DO) levels will need to be pretty good.

These really aren't the type of questions you should be relying on forums such as this one to answer IMO. Raising trout in Dubai would require some serious technical assistance in the form of environmental controls. In addition to having a decent working foundation of the "basics" of trout rearing in raceways. Someone local with expertise and/or knowledge in such a field would be most helpful, particularly if they have a good grasp on the basic principles of aquaponics (in order to better modify and adapt such knowledge to an aquaponics scenario). 

Good luck with your en devours Kaveh. 

[kaveh arabdashti]

Thanks Vlad for reply and valuable information which you share with me, in fact I am software developer and we developed a software for management of trout farms, I need these information for my software improvement , now I can incorporate your methodology for calculation of maximum biomass and I will add related alarms for user when this parameter is out of acceptable rang , for question 1 and 2 , are there any methodology which I can convert it to algorithm and subsequently code and application ?

at present our software has complete features for receiving and use water factors like temperature,PH, oxygen,flow rate(liter/second) and bio-metric information , as well as , feeding planing and reporting and calculation of FCR and complete features for inventory and sale management, so I have sufficient data for such a analyzing ( which trout farmers want from me) but problem is I do not know HOW!