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Revista mexicana de ciencias agrícolas

versión impresa ISSN 2007-0934

Rev. Mex. Cienc. Agríc vol.7 no.5 Texcoco jun./ago. 2016



Determination of relative fish plant in tomato (Licopersicum sculentum L.) production in aquaponic system

Salvador Villalobos-Reyes1 

Enrique González-Pérez1  § 

1Campo Experimenta Bajío. Instituto Nacional de Investigaciones Forestales, Agrícolas y Pecuarias. Carretera Celaya-San Miguel de Allende km 6.5, Colonia Roque, Celaya, Guanajuato, México. C. P. 38110.


In the last decade, Mexico has taken aquaponics economic importance, but information on this production system is limited. Our aquaponics system was designed to determine the relationship fish-plant suitable for the production of tomato. In tanks with 450 L of water fingerlings they were seeded with initial individual weight of 0.45 g in three densities 120, 80 and 40 fish m-3. The fish were fed daily at a rate calculated on 7% of body weight per fish. The commercial feed 46% protein was used for a month and 28% protein for two months remaining. A total of 48 tomato seedlings were transplanted into three beds growth (16 plants per bed) 10 days after the stocking. Fish survival was 100%, feed conversion factor was 1.18 and the final weight per fish was 62 g. With the 20:1 ratio was obtained plants with average stem length of 160.6 cm, greater number of fruits (9) and average yield of 2.5 kg pta-1. The nutrient concentration in water was below the permitted limits, however, the low concentration of K and the absence of Fe and B affected the development of the plant after 90 days.

Keywords: plant growth; protein; nutrient; water quality


En la última década, la acuaponia en México ha tomado importancia económica, pero la información sobre este sistema de producción es limitada. Nuestro sistema de acuaponia fue diseñado para determinar la relación pezplanta adecuada para la producción de tomate. En tanques con 450 L de agua se sembraron alevines de tilapia con peso individual inicial de 0.45 g en tres densidades 120, 80 y 40 peces m-3. Los peces fueron alimentados diariamente a una tasa calculada sobre 7% del peso corporal por pez. Alimento comercial de 46% de proteína se usó durante un mes y de 28% de proteína para los 2 meses restantes. Un total de 48 plántulas de tomate fueron trasplantadas en tres camas de crecimiento (16 plantas por cama) 10 días después de la siembra de peces. La sobrevivencia de peces fue de 100%, el factor de conversión alimenticia fue de 1.18 y el peso final por pez fue de 62 g. Con la relación 20:1 se obtuvo plantas con longitud promedio de tallo de 160.6 cm, mayor número de frutos (9) y rendimiento promedio de 2.5 kg pta-1. La concentración de nutrimentos en el agua estuvo por debajo de los límites permitidos, sin embargo, la baja concentración de K y la ausencia de Fe y B afectaron el desarrollo de la planta después de 90 días.

Palabras clave: calidad de agua; crecimiento vegetal; nutrimento; proteína


The aquaculture systems continually generate large amounts of waste, so from the use of these wastes can be obtained another product that generates in turn an additional financial gain. By integrating the aquaculture system with hydroponics a production model called aquaponics, defined as the cultivation of fish and plants in a recirculation system (Nelson, 2008), which could serve for sustainable food production in polyculture creates what increasing diversity and final production, and the possibility of obtaining phytosanitary quality products and with significant socioeconomic impacts to obtain economic benefit (Diver, 2006).

Aquaponics has advantages over other production systems such as aquaculture recirculation system and hydroponic system using inorganic nutrients. In aquaponics hydroponics component serves as a bio filter, so it is not necessary to use other filters and recirculation systems. Aquaponic crops control the accumulation of residual nutrients from aquaculture, reducing the consumption of fertilizer and water, without detracting from the quality and productivity of crops (Roosta and Mohsentan, 2012). The fish feed provides most of the nutrients required for plant growth.

Most fish species used 20-30% of nitrogen (N) supplied by the diet (Piedrahita, 2003; Schneider et al., 2005), this means that approximately 70-80% of the N supplied by the power is released as waste into water (Krom et al., 1995), the ammonium the end product of protein breakdown that fish digest their food and are dissolved in water through their feces. The efficiency of nitrification (a crucial process in aquaculture, that reduces the level of ammonia, which is a major cause of toxicity for fish farming) is higher in alkaline solution, pH 7.5-8, which is the reason relatively high pH in most aquaculture facilities (Savidov, 2004).

However, the plant growth can be affected by the high pH (above 7), while at pH 5.8 it is considered that no better availability of nutrients in hydroponics, but the development and growth of fish affected (Boyd, 1992). In previous studies it is reported that in the aquaponic system waste fish provide nutrients to plants in low phosphorus (P), potassium (K), sulfur (S), iron (Fe) and manganese (Mn) (Seawright et al., 1998; Graber and Junge, 2009). Of the various systems aquaponic recirculation (Diver, 2006; Rakocy et al., 2006), for growing species such as tomato use bed system recommended by the management that requires the cultivation, as the tomato in aquaponics it is more difficult to produce compared to deciduous crops, due to increased demand for nutrients at different stages of growth (Sikawa and Yakupitiyage, 2010).

From germination to the development of the first flowers (6 weeks), the nutritional needs of the plant are constant and when the plants begin to produce fruits require more Ca, Mg, and K (Nelson, 2008). There is limited information on production and nutrient demand tomato aquaponics system, previous studies by various authors focus on the behavior of nitrogen in the system, but none is set few fish are needed to generate the amount of nutrients that demand a plant. Based on the above, the objective of this research was to determine the relationship fish-plant and its influence on the growth, development and yield of tomato plants produced in aquaponics system.

Materials and methods

Experimental site

The research was conducted in a greenhouse tunnel intermediate technology within the premises Horticulture Program Experimental Bajio, INIFAP, located in Celaya, Guanajuato at 20° 30´ north latitude and 100° 49´ west longitude to 1 750 msnm.

Aquaponic system

The system was composed of three identical aquaponic units (Figure 1). Each unit consisted of a pond fish growth, a water pump, two filters and a bed of growing plants, with a total water volume of 300 L. The fish growth unit was a polyethylene tank 450 L with aeration distributed by an air pump 3 W connected to two air vents (2 L min-1), located in the center of the tank. The two filters (plastic boat 20 L) containing tezontle screening mesh of 12 mm to a thickness of 30 cm placed within polyethylene mesh 30 months h white 50 cm2, which were drawn every two months. In the fish tank was installed submersible pump vane 40 W continuously propelled by the solution recirculating system through polyethylene tubing connections 16 mm.

Figure 1 Schematic of the experimental aquaponics unit and its components. A) Recirculation system; B) Unit fish growth; and C) Unit of plant growth. 

The recirculation cycle began with the water supply to the first filter which waste particles are retained, after passing through the filter water is distributed into the bed of growing plants by micro-tubin flexible polyethylene 4mm connected to the pipe polyethylene and placed at 5 ± 1 cm away from the plants, after passing through the bed of growth, the water was captured and directed to the second filter, and later return to the fish tank located at the lowest point in the system. The constant flow of micro-tubin was 8 L h-1. The plant growth unit was a metal tray where they were used as pots polyethylene bags containing 32 L tezontle previously disinfected with quaternary ammonium (800 ppm). The volume of water in the system was kept constant with replenishments every which lost more than 10% of the total volume.

Physico-chemical characterization of water

To monitor the concentration of nutrients in the water system, samples were taken every 15 days. Three samples with 3 replications were taken at two points in the system: a) pond and b) download site and pH, electrical conductivity, ammonium, nitrate, phosphorous, potassium, calcium and magnesium was determined. For ammonia and nitrates portable spectrophotometer model DR/2400 Hach®, phosphorus (P) was determined with the method of Bray and Kurts (1945), potassium (K) by the method of saturation (Hesse, 1971) was used, and the contents of calcium and magnesium bases by atomic absorption (Thomas, 1986).

Fish farming

For the experiment 240 tilapia fish (Oreochromis niloticus x O. aureus) were used with an initial single weight of 0.45 g, sexually reverted with fluoxymesterone (7.5 mg kg-1 of fish) for 25 days. To determine the relationship fish-plant three densities of 120 fish, 80 and 40 fish m-3 in each unit aquaponics were cultured with an initial total biomass of 56.4, 37.6 and 18.8 g fish m-3, respectively. In the initial stage and fattening fish they fed a commercial diet puritilapia (Table 1) containing 45% and 28% crude protein, respectively. The fish were fed daily, twice a day, at 8:00 and 13:00 h at a rate calculated on 7% of body weight per fish. The commercial feed 46% protein was used for a month and 28% protein for 60 days. Stocked fish were sampled every two weeks to adjust the food ration and every 30 days was determined the average weight per fish with a precision scale (0.1 mg; ESCALI-P115C, USA). The average weight gain per fish (g), density (kg m-3) and survival (%) was determined 90 days.

Table 1 Approximate composition of food used to feed tilapia in the initiation stage and fattening. 

Composición Peso fresco (%)
Inicial Engorde
Proteína 45 28
Grasa 8.0 5.5
Cenizas 10 10
Fibra 5 5
Humedad 14 14

In parallel the growth rate was determined (Cifuentes et al., 2012).

K= 100 (W/L3)

Where: W= body weight (g), and L= length (cm).

Development and plant growth

Used ball-type tomato var. Springel produced in styrofoam trays of 330 cavities containing enriched peat (Sunshine Growth, Canada). The seedlings were kept in a greenhouse at an average temperature of 26 ± 2 °C and RH of 42% for 16 days. The trays were watered twice a day and fertilized once a day with 1.5 L of the nutrient solution proposal by Villalobos et al. (2012). Subsequently, a total of 48 seedlings (four per bed) were transferred and grown in the beds of growth of the system at 28 ± 2 °C and RH of 42-55% for 90 days. The stem length (TL; cm), number of leaves (NH), stem diameter (DT; cm), number of bunches (NR), number of fruits (NF) and yield (kg pta-1) were recorded 90 days after.

Experimental design and statistical analysis

The experiment consisted of three treatments (densities of 120, 80 and 40 of fish m3) established under a completely randomized design with four replications. The variables recorded data underwent to an analysis of variance and by Tukey mean test (p≤ 0.05) with statistical program SAS (SAS, 2013).

Results and discussion

Physico-chemical characterization of water

The characterization of water in ponds showed slight variation in some parameters during the experiment (Table 2). The parameters in terms of greater importance for the production of fish [nitrate (NO3-), pH and EC] were below the tolerance limit, except for the pH was slightly below 7 in some periods of time experiment, especially when the water level evaporated and/or consumed is compensated (Boyd, 1992; Boyd and Tucker, 1998; Graber and Junge, 2009).

Table 2 Some indices registered water quality and tolerance limits for the production of fish in aquaponics system. 

Parámetro Relación pez-planta Límite de tolerancia*
30:1 20:1 10:1
pH 7.8 7.0 6.9 7-8
EC (Ms cm-1) 0.22 0.19 0.16 < 12
Temperatura del agua (°C) 22 ± 2 22 ± 2 22 ± 2 26-28
NO3-N (mg L-1) 7 6 4 < 150
NH4-N (mg L-1) 0.3 0.2 0.1 < 1.0
K (mg L-1) 12 8 6 -
P (mg L-1)-1 6.5 5 3 -
Ca (mg L-1) 18.5 10 10 < 350
Mg (mg L-1) 2.6 2.6 2.3 -
Fe (mg L-1) 0.001 0.001 0 -

*Boyd, (1992); Boyd y Tucker, (1998); Graber y Junge, (2009).

Campos et al. (2013) indicates that the accumulation of nitrate in aquaponics systems has a negative effect on fruit, because they produce less fruit while there is a vegetative growth in excess, so it is concluded that in cultures of higher demand as tomato would not accumulation NO3. The values of ammonium (NH+4 -N) were below the limit of tolerance which allowed a good development without introducing fish mortality due to toxicity. Zweig et al. (1999), mentions that in tropical regions fish tolerate a maximum of 0.1 mg of NH+4 -N L-1 and when it exceeds mortality occurs due to toxicity. The concentration of Ca and Mg was below the limit of tolerance (Table 2), so that the total water hardness was low according to that mentioned by Su and Quintanilla (2008), who set from 20 to 350 mg of Ca L-1 as the optimum range for a good development of tilapia in aquaponic systems.

However, the values of Ca and Mg registered are insufficient when crops require greater concentration of these nutrients are established, as is the case of tomatoes, which are deficient in the fruit, especially of Ca (Schneider et al., 2005). In contrast, potassium values were within permitted for aquaculture, but below those required by tomato plants (Boyd and Tucker, 1998; Roosta and Mohsentan, 2012). While the concentration of P and Fe was not limiting for the development of fish and plants (Seawright et al., 1998).

Fish farming

The biometry showed an average initial weight of 0.45 g and fish harvesting biomass obtained the final was better in the density of 80 fish m-3 with an average fish biomass per 62 g for a production of total biomass of 4.9 kg fish m-3, and the densities of 120 and 40 was 59 g (Table 3). The final fish biomass was lower than the growth that occurs in intensive aquaculture systems. Poot-Delgado et al. (2009), it has mentioned that tilapia rapid growth compared to other fish, reaching each weighing 166 g in 150 days density of 3-5 m2 fish when fish are stocked with an initial weight of 10 g is maintained at a temperature of 26-28 °C. For our study it is considered that the final weight obtained was influenced by the temperature during the experiment was 4 °C below 26-28 °C, temperature is considered optimal for the growth of tilapia in combination with high population density (Su and Quintanilla, 2008).

Table 3 Growth behavior of tilapia grown in combination with tomato after 90 days aquaponics system. Spring, 2014. 

Densidad peces m3 Relación pez:planta PIP (g) PFP (g) DI (g) DF (kg)
40 10:1 0.47* 59.7 18.8 2.3
80 20:1 0.47 62.2 37.6 4.9
120 30:1 0.47 59.1 56.4 7.1

PIP= peso inicial de pez; PFP= peso final de pez; DI= densidad inicial; DF= densidad final. *Valores medios de cuatro repeticiones.

The survival was 100%, which indicated that the system water was of good quality. The total feed conversion factor was 1.18. The growth rate was 1.5, lower growth reported (1.7 g) by Rakocy et al. (2004). In contrast, Shnel et al. (2002) report a feed conversion ratio of 2.03, a growth rate of 1.42 g, an initial density of 10.4 kg m-3 and a total of 81.1 kg m-3, after 331 days of culture.

Development and plant growth

The growth of tomato plants in aquaponics showed significant differences (p≤ 0.05) for stem length (LT) and number of fruits (NF), whereas the number of leaves, stem diameter and number of bunches not there were differences (Table 4). The fish plant ratio 20:1 was better at LT and NF, indicating that there is a point of proficiency in the assimilation of nutrients in the water system. The LT and the lower NF in the ratio 30:1 was possibly caused by the pH (7.8) of the water was higher than in the other treatments (Table 3). The salt concentration in the fish density affect the absorption of nutrients such as K, Fe and B, because in alkaline pH availability is limited to be set or displaced by other elements such as Al, Mg, among others, they accumulate in the roots so that limit their absorption. In addition, in aquaponic systems the concentration of K and Fe are present in low concentrations.

Table 4 Effect of relative fish plant on the growth of tomato plants grown in aquaponics system after 90 days. Spring, 2014. 

Parámetro Relación pez-planta LT (cm) DT (cm) NH (#) NR (#) NF (#) Rendimiento kg planta-1
120 pez m-3 1:30 138.6b* 1.27a 33a 3a 6b 1.46b
80 pez m-3 1:20 160.6a 1.35a 36a 4a 9a 2.56a
40 pez m-3 1:10 129.9b 1.05a 34a 2a 6b 0.77b
DMS 22 0.3 2 1 3 0.71

LT= longitud de tallo; DT= diámetro de tallo; NH= número de hojas; NR= número de racimos; NF= número de frutos; DMS= diferencia mínima significativa. *Medias dentro de columna seguida por la misma letra no son diferentes estadísticamente Tukey (p≤ 0.05).

The requirement K is low for the development of the fish, so that in the diet is not included, therefore, in the system water concentration is low (Graber and Junge, 2009), while for growing tomato demand is higher. According to Kaya et al. (2001), providing K should be as foliar radical because the part is subjected to salinity stress conditions. The concentration of Fe was in appreciable, which negatively influenced the growth of plants, because this element along with K increase vegetative growth in tomato plants grown in aquaponics (Roosta, 2011).

The largest number of fruits in the ratio 20:1 was because on average the plants produced a bunch more, which is attributed to the concentration of N that was in sufficiency since most of the nutrients were at low but stable concentrations except K and Ca. However, the best treatment some fruits of the fourth cluster showed visible symptoms of deficiency Ca. On the other hand, the concentration of Fe in hydroponic systems have only positive effect on plant growth when in sufficiency and this study had low concentration (0.001 mg L-1). It is noteworthy that most of the nutrients (Table 2) present for the system to be constantly produced by microbial activity that acts on the decomposition of fish excreta can set the nutrients in the waste, and modification pH and CE nutrient availability is affected (Rafiee and Saad, 2005; Nelson, 2008).

In all treatments after 90 days deficiencies of K, Ca and Fe were presented, which caused loss of turgor in the plant, flower abortion and reduced fruit size. This corroborates the results obtained by Roosta and Hamidpour (2011), who mentioned that it is necessary to complement foliar supply of these nutrients as they are present in concentrations that do not meet the demand in intensive crops such as tomatoes. Graber and Junge (2009) mention that the concentration of K in water aquaponic is 45 times lower than in conventional systems, which in hydroponics is an important factor since it affects the growth of plants, and results in a poor plant development which affects fruit quality. On the other hand, the presence Ca unassimilable forms fruits generated with cracks and/or typical obscure points of deficiency (Graber and Junge, 2009). This associated with alkaline pH of the solution (Table 2) limits the availability and absorption of K and Fe affecting crop development (Roosta, 2011).


This study showed that the gain in biomass of tomato plants is restricted to 90 days after established in the system. With the fish relation plant 20:1 a good vegetative growth of tomato plants was obtained, although it is necessary to do more detailed studies on implementation strategies for the supplementary supply of K, Ca, Fe, and other nutrients, because that the concentration of these must be balanced to meet the demand of nutrients required for the growth of fish and plants.

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Received: February 2016; Accepted: May 2016

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