The calculation of weight and mass in aquaculture systems is of great importance, since with this task, it is decided when to harvest; generally, the above is manipulating the body manually, which causes stress in the fish body. Said stress can be maintained in the fish body for several hours. To solve this problem an improved method was implemented using artificial intelligence, near-infrared spectroscopy camera, Haar classifiers, and a mathematical model. Hardware and software were designed to get a photograph of the fish in its environment in real conditions. This work aimed to obtain fish weight and fish length in real conditions to avoid the manipulation of fish with hands for the process mentioned, avoiding fish stress, and reducing the time for these tasks. With the implemented hardware and software adding an infrared light and pass band filter for the camera successfully, the fish was detected automatically, and the fish weight and length were calculated moreover the future weight was estimated.

In this research, effect of productive stages in nitrogen and phosphorus excretion in wastewater from hyperintensive tilapia (Oreochromis niloticus) culture was evaluated. Fish were cultivated considering three development stages (fingerling of 1.79 g, juvenile of 36.13 g, and adult of 72.96 g). Nitrite, nitrate, ammonium, and phosphorus concentration were determined in order to know the amount of nutrients excreted per productive stage of the fish at a high stocking density. Biometric data were recorded during the experiment with the purpose of determining the growth behavior of fish, as well as the measurement of the aerobic metabolism. Results showed that survival, growth, and health of fish are not affected by hyperdensity of culture; as well, combined catabolism of proteins and lipids was presented as substrates for energy with value for O:N ratio ranging between 20 and 60. In addition, higher concentration in excretion of nitrogen compounds and phosphorus per gram of fish was recorded in wastewater from a hyperintensive culture in fingerlings than in juveniles and adults. These results suggest the use of this wastewater in the early stages of fish growth, aiming to enhance sustainable systems with maximum use of the resources, such as aquaponics systems.

The fish feed used in aquaculture systems has many nutritional factors like protein, fat, fiber, ash, and humidity; from these factors, one of great importance is protein. The protein of fish feed is obtained from fish meal, and the demand for fish meal has increased; this induces to increase the price. Many pieces of research have been done about this topic to mitigate this problem. This research shows the differences between three commercial foods of the different processes with the same quantity of protein, using tilapia Oreochromis niloticus, to prove any difference between NO2-, NO3-, and NH4+. Nitrogen compounds were determined with HACH methods for the DR6000 spectrophotometer. Biometric data were registered throughout the growth of fish, along with measure aerobic metabolism. Results have shown that has better outcomes related to low excretion of nitrogen compound was medium-cost fish feed (MCFF). It also has sound effects associated with the length-weight relationship; that could be connected to these fish feed's protein sources.

In recirculating aquaculture systems (RAS), the water exchange rate influences the removal of waste compounds. However, the inappropriate exchange rate favors the presence of stress factors, causing alterations in the cultured organisms. Therefore, the aim was to determine the effect of the water exchange rate in the different productive stages (fingerling, juvenile, and adult) of Nile tilapia (Oreochromis niloticus). Three exchange rates were used: rates of 1.2 (T1), 2.8 (T2), and 5.3 (T3) tank volume h-1. The following were established as response variables: growth rate (GR), survival rate (SR), feed conversion rate, protein efficiency, and condition factor. Likewise, cortisol and glucose concentrations were established as explanatory variables. The results suggest that in the fingerling stage, the T2 treatment contributes most to the productive performance (GR = 40.24 g and SR = 95%), keeping low levels of cortisol and glucose (6.76 ng mL-1 and 33.73 mg dL-1). In the juvenile stage, T3 treatment shows the best result both in productive performance (GR = 117.69 g and SR = 90%) and in cortisol and glucose concentrations (35.13 ng mL-1 and 70.67 mg dL-1). Finally, all treatments present cortisol and glucose levels above the normal range in the adult stage, T1, where the highest productive performance is presented (GR = 90.06 g and SR = 95%). The information leads us to consider the variation in the exchange rate in a RAS through the different stages of the Nile tilapia to maintain the favorable conditions that lead to the highest performance.

In this research, the effect of different productive stages of tilapia (Oreochromis niloticus) in a hyper-intensive aquaculture system on the growth of tomatoes was evaluated. Fish were cultivated in a final density of 80 kg m3 considering three development stages (an average of fingerling of 1.487 g, juvenile of 62 g, and adult of 203.75 g, respectively). The quality of water was measured by determining temperature, pH, electric conductivity, and dissolved oxygen. Biometric data were registered throughout the growth of fish and tomatoes. Results showed that the survival, growth, and health of fish are not affected by the hyper density of culture; as well as the quality water was maintained under acceptable conditions for the development of organisms. Besides, it was obtained that the early productive stages (fingerlings and juveniles) gave the best results for tomato growth. These results suggest using the wastewater from fingerlings and juveniles of a hyper intensive recirculation aquaculture system to produce hydroponic tomato; to achieve sustainable production systems with maximum use of the resources.