Tilapia Farming Research Articles

Characterization of Fish Farming Practices and Performance: Baseline Study and Implications for Accelerating Aquaculture Development in Ghana

Over the past decade, the aquaculture sector in Ghana has experienced tremendous growth—driven mainly by large-scale cage farms—but it has been unclear how the rural poor have shared in this growth. A research project has been initiated to help diagnose, design, and test interventions for better inclusion of the rural poor, women, and youth in the tilapia value chain. This report describes the baseline data on 603 small-scale tilapia farmers in Ghana. The data collected during two-hour face-to-face interviews during May–July 2019 are disaggregated by socioeconomic indicators, gender, and age group. Baseline data show that 9 percent of farm managers and owners were women, and an additional 9 percent of farms engaged women in some decision-making. Moreover, women contributed 16 percent of family labor and 5 percent of hired labor on farms. Youth represented 14 and 24 percent of owners and managers, respectively, but contributed 68 percent of the total family and hired labor on farms. A large majority of managers and owners had at least high school education, with a third of owners and a quarter of managers attaining at least a college degree. In Brong Ahafo and Ashanti regions especially, most farmers engaged mainly in crop farming and non-farm businesses as their main livelihood, with fish farming as a small contributor to overall household income and livelihood. Farmers in all regions had poor record-keeping and management practices and low compliance with sanitation, fish health, and food safety standards. A wide variety of input usage, management practices, and performance was observed among fish farms. As a result, the profitability of fish farms was also wide-ranging, between –12.00 and 46.00 cedi per m2, with an average of 8.82 cedi per m2. Despite wide variability in production and profits, the majority of farmers experienced positive profits. On average, a farmer received a profit of 2.4 cedi per kilogram of tilapia produced or a 27 percent profit margin. These encouraging figures indicate that farmers who adopt good aquaculture practices can achieve respectable profits.

Application of Tilapia Cultivation Biofloc Technology For Utilization of Non-Productive House Yards

The community partnership program, titled Tilapia fish cultivation with Bioflock technology, was carried out in Gowa Regency in the Juluatia farmer group chaired by Ms. Kasmawati, aimed at empowering farmer groups to become productive entrepreneurs. This activity has short-term programs, namely: 1) Optimizing unproductive home yards; 2) Improve the knowledge and skills of tilapia farming. This activity program is carried out for 8 (eight) months with 1 (one) The Community Partnership Program partner. The stages of the community partnership program implementation include the stage of surney preparation and site review, analysis of potential and problem partners, and implementation of PKM activities. The technology applied in this PKM activity is Bioflock technology in aquaculture minimize the use of artificial feed, as well as the efficient use of water. From the results of the implementation of this PKM produced 3 (three) units of Bioflock tilapia ponds, increasing science and technology in the community, especially in the Juluatia farmer group

Can histology and haematology explain inapparent Streptococcus agalactiae infections and asymptomatic mortalities on Nile tilapia farms?

The aim of this study was to characterise possible histopathological and haemato-immunological changes after subclinical infection by S. agalactiae S13 serotype Ib. One hundred juveniles of Nile tilapia with average weight of 45 g were distributed in ten 90 L experimental units. After the acclimation period 25 fish were euthanised, and fragments of liver, spleen and posterior mid-intestine tissue were sampled to verify the integrity of the organs and blood samples taken to check the haematological profile. Fifty animals were used to verify the optimal dosage for the challenge. The remaining 25 fish were infected with S. agalactiae S13. After 96 h, tissue fragments from the liver, spleen and posterior mid-intestine and blood samples were collected. The analyses revealed that, 96 h after contagion, S. agalactiae S13 serotype Ib caused subclinical lesions in the liver and spleen that are not commonly described as pathognomonic, in addition to haematological alterations. These results allow a better understanding of sudden recurrent mortalities in Brazilian tilapia farms, since the serotype Ib of S. agalactiae causes inapparent infections and can remain lodged in internal organs and cause irreversible lesions and haemato-immunological alterations, therefore compromising physiological functions vital for the health of fish without revealing external clinical signs in the animals.

Identification of a Novel Ichthyic Parvovirus in Marine Species in Hainan Island, China.

Parvoviruses are a diverse group of viruses that are capable of infecting a wide range of animals. In this study, we report the discovery of a novel parvovirus, tilapia parvovirus HMU-HKU, in the fecal samples of crocodiles and intestines of tilapia in Hainan Province, China. The novel parvovirus was firstly identified from crocodiles fed with tilapia using next-generation sequencing (NGS). Screening studies revealed that the prevalence of the novel parvovirus in crocodile feces samples fed on tilapia (75–86%) was apparently higher than that in crocodiles fed with chicken (4%). Further studies revealed that the prevalence of the novel parvovirus in tilapia feces samples collected at four areas in Hainan Province was between 40 and 90%. Four stains of the novel parvovirus were identified in this study based on sequence analyses of NS1 and all the four strains were found in tilapia in contrast only two of them were detected in crocodile feces. The nearly full-length genome sequence of the tilapia parvovirus HMU-HKU-1 was determined and showed less than 45.50 and 40.38% amino acid identity with other members of Parvoviridae in NS1 and VP1 genes, respectively. Phylogenetic analysis based on the complete helicase domain amino acid sequences showed that the tilapia parvovirus HMU-HKU-1 formed a relatively independent branch in the newly proposed genus Chaphamaparvovirus in the subfamily Hamaparvovirinae according to the ICTV’s most recent taxonomic criteria for Parvoviridae classification. Tilapia parvovirus HMU-HKU-1 likely represented a new species within the new genus Chaphamaparvovirus. The identification of tilapia parvovirus HMU-HKU provides further insight into the viral and genetic diversity of parvoviruses and its infections in tilapia populations need to be evaluated in terms of pathogenicity and production losses in tilapia farming.

Growth of Chlorella vulgaris using wastewater from Nile tilapia (Oreochromis niloticus) farming in a low-salinity biofloc system

The present study aimed to analyze the growth of Chlorella vulgaris in the effluent of a Biofloc Technology (BFT) system used in the Nile tilapia fingerlings farming. The conditions were cultivated by 10 days at 25 ± 2ºC, 90 μmol photons m−2 s−1 irradiance, under constant aeration (without addition of CO2), and with different BFT effluent proportions (0, 50, and 100%). After 24 hours of the inoculation that marked the beginning of the experiment, the development and multiplication of the cells were verified, demonstrating that the BFT effluent used in the Nile tilapia farming was favorable for the cultivation of the microalga Chlorella vulgaris. As expected, the Provasoli culture medium presented the best performance (1,520 ± 75 104 cells mL-1) in relation to the growth of the microalga. However, during the first four days of cultivation, C. vulgaris showed higher growth in treatments containing BFT effluent. C. vulgaris removed 93.6% of the nitrate contained in the BFT effluent. The results of the present study showed the potential use of C. vulgaris on Integrated Multi-Trophic Aquaculture with Nile tilapia fingerlings. In addition to removing nitrate and other nitrogen compounds, C. vulgaris biomass could be used to feed zooplankton or Nile tilapia larvae.

The Influence of Entrepreneurial Spirit towards Farm Performance of Fish Cultivation Nile Tilapia, Sleman Regency, Indonesia

Farmers' entrepreneurship is very important as a new approach to improving farm performance is based, among others, on entrepreneurial characteristics. Entrepreneurship is the ability to create and provide value-added products. Fisheries are increasingly in demand because people are becoming aware of the many benefits of fish, especially for health. The objective of this research was to determine the performance of fish cultivation in Nile Tilapia farming. The research location is determined purposively and the total sample is 150 respondents. This methods of data analysis is using analysis of SEM (Structural Equation Modeling). The results showed that Entrepreneurial spirit influences farm performance, so it can develop a tilapia cultivation business as well as income, profits, business feasibility. Members of tilapia aquaculture groups on average have high income and profits, so this business is worthy of the effort.

Tilapia lake virus disease: Phylogenetic analysis reveals that two distinct clades are circulating in Israel simultaneously.

Tilapia lake virus (TiLV) is an emerging viral disease that affects several tilapia species in different countries since 2014. In 2017-2018, 129 samples were collected from 14 tilapia farms in Israel. Ninety samples represented TiLV-suspected cases (TSC), and 39 were used as control samples (CS). RT-qPCR was performed on 89 and 39 duplicate brain and liver tissue samples from TSC samples and CS, respectively. TiLV was diagnosed in 37 (40.1%) of TSC, and two of the CS samples (5%) were also positive for TiLV. Additional validation RT-PCR was performed on positive samples, and amplified products were sequenced. Maximum-likelihood phylogenetic analysis of segment-3 of 25 selected sequences revealed two distinct clades: one virtually identical to sequences from India and the second closely related to isolates from Ecuador, Thailand, Egypt and Peru, apparently imported to Israel from Thailand. Thus, our results indicate that at least two distinct clades of TiLV are circulating in Israel simultaneously. As of today, the number of TiLV sequences available in free publicly accessible databases is limited. Nevertheless, our study provides new molecular epidemiology baseline for further epidemiological studies of TiLV.

Resource use efficiency in tilapia production in Central and Southern Malawi

The aquaculture sector in Malawi has not shown significant growth in terms of production and productivity. This study applied the translog stochastic frontier to determine the technical efficiency in tilapia production in Malawi. Multi-stage sampling procedure was used to select 211 tilapia farms for the study. The determinants of tilapia output in Malawi are seed, fertilizer input and farm size. The mean technical efficiency estimate was 66% indicating that the tilapia producers have a yield gap of 34%. Sex of producer, age, household size, access to extension, training and access to credit are major factors influencing the efficiency level of tilapia producers. On average, tilapia production is carried out under the decreasing returns to scale. Tilapia producers grossly under-utilized feed, fingerlings, fertilizer, and farm size and over-utilized Labor. Government and other stakeholders should ensure widening access to extension, training fish farmers, empowering women tilapia producers, widening access to credit and financing sources to enhance tilapia production in Malawi.

Optimizing diets to decrease environmental impact of Nile tilapia (Oreochromis niloticus) production

Aquaculture is one of the most thriving animal production sectors, and Nile tilapia (Oreochromis niloticus) farming represents 8% of total finfish culture. However, the industry sustainability depends on the development of cost-effective and environmental friendly feeds. This study aimed to reduce dietary protein levels in diets for juvenile tilapia and to minimize diet environmental impact while maximizing biological efficiency. A growth trial was performed using five isoenergetic plant protein-based diets with decreasing levels of crude protein: 360, 340, 320, 300 and 280 g/kg diet (D360, D340, D320, D300 and D280, respectively). Dietary protein utilization was assessed by metabolic trials using a radiolabelled amino acid mixture. Tilapia in all treatments showed similar growth performance and feed intake. Feed conversion ratio was significantly higher in fish fed the D280 than the D360 diet, while no differences were found for other treatments. Protein retention was significantly higher in tilapia fed the D300 than the D360 diet. Amino acid catabolism increased in fish fed the D360 diet, though without significant differences in muscle amino acid retention. This study demonstrates that dietary protein levels can be reduced to 300 g/kg diet without hindering tilapia growth and feed conversion ratio, while reducing environmental nitrogen losses.

Technical efficiency of different farm sizes for tilapia farming in China

China is the world's largest tilapia producer. This study uses the stochastic frontier function in the Cobb–Douglas model to evaluate a production frontier for tilapia aquaculture and analyses the relationship between farm size and production efficiency in China. A random sample of 300 tilapia farmers was surveyed in the main tilapia-producing areas to study their economic efficiencies. The percentage distribution of tilapia farm technical efficiency was determined, with an average efficiency of 79%, which showed that the sample tilapia farmers operate at 21% below the production frontier and hence that they still have a chance to achieve targeted yields. The technical efficiencies of two categories (≤1 ha and >1 ha) were 78.82% and 79.27% respectively. A second-stage analysis investigated the relationship between farm size and technical efficiency and showed a positive relationship between farm size and production efficiency based on the ordinary least-squares model. The optimal farm size was found to be 7.50 ha. This study proposes strategies such as enlarging the farming scale moderately, thereby achieving the advantage of economies of scale, and enhancing the competitiveness of the tilapia industry in China.

Mineral content in local feed ingredients used by fish farmers in four different regions of Tanzania

This study investigated the content of selected minerals (P, Ca, K, Na, Mg, Fe and I) in local feed ingredients used by tilapia fish farmers in Tanzania. Analyses were performed on 26 local feed ingredients collected at four different geographical locations in Tanzania (Dar es Salaam, Morogoro, Mbeya and Mwanza). The samples were taken randomly from fish farmers, fish feed producers, fingerling producers and animal feed shops or centers near fish farms in each region. The results showed a wide range of mineral concentrations. The highest levels of P was found in fish skeletons (17.8 g kg-1), of Ca in limestone (107.3 g kg-1), of K in gallant soldier (51.0 g kg-1), of Na in marine shrimp (Exhippolysmata oplophoroides) (11.7 g kg-1), of Mg in prawn head waste (4.2 g kg-1), of Fe in azolla (2355 mg kg-1) and of I in full fat soybean (447 mg kg-1). The data on mineral content in feed ingredients can be used as a platform for better-targeted feed formulation for tilapia farming systems. In conclusion, the data suggest that if more than two ingredients are used in the diet, this may be sufficient to meet the mineral requirements of all cultured tilapia species and their hybrids, without inclusion of any mineral premix.

Antibiotic residues in farmed raised tilapia (Oreochromis niloticus) of southwest region of Bangladesh

The objectives of this investigation were to seek out the residue level of nitrofurans and chloramphenicol in cultured tilapia muscle in south west region of Bangladesh. Ninety samples were collected randomly from various fish farm of different Upazillas of Khulna, Satkhira and Bagerhat districts during August-December, 2017, where each district was contained 30 samples. Antibiotic residues level present in the animal muscles were detected using ELISA in the Quality Control Laboratory of the Department of Fisheries, Khulna, Bangladesh. To collect information about the status of feed type questionnaire interviews were performed during sample collection from the respective farmers. The overall results revealed that nitrofuran metabolites and CAP residue existed in all the samples within the MRL (Maximum Residue Level) with the exception of 3.33%, 6.66% and 3.33% samples of Khulna, Bagerhat and Satkhira district respectively. Antibiotic residue data showed all nitrofuran metabolites like SEM, AOZ, AMOZ, AHD and CAP were present in all samples in which SEM was highest in Shatkhira district and lowest in Khulna district. In case of AHD, highest residue was found in Khulna and lowest was Satkhira district. Additionally, AOZ was highest in Khulna district and lowest in Bagerhat district and AMOZ was highest in Bagerhat district and lowest Satkhira district. CAP was found highest in Satkhira district while that was lowest in Bagerhat district. The results of the also revealed that contamination of nitrofuran metabolites and chloramphenicol were more in tilapia farms where home-made feed was used compared to commercial feed.
 Asian Australas. J. Biosci. Biotechnol. 2019, 4 (2), 102-108

EFFECT OF THE C:N RATIO ON <i>Daphnia magna<i> (Straus, 1820) PRODUCTION USING TILAPIA FARMING WASTEWATER

The purpose of this study was to produce Daphnia magna in wastewater from Tilapia farmed in a biofloc system, to evaluate three different carbohydrate:nitrogen ratios. The experiment was conducted for 30 days following a completely randomized experimental design, with the three treatments: C:N 10:1, C:N 15:1 and C:N 20:1, all fed with Chlorella vulgaris. The physical-chemical variables of the water analyzed were: temperature, dissolved oxygen (DO), pH, TAN, NO2 , hardness and alkalinity. The following growth variables of the Daphnia were also evaluated: Maximum average density (MAD), Maximum density day (MDD), Specific growth rate (SGR), Doubling time (DT) and yield (Y). The water quality variables remained in the range of ideal conditions for the species, presenting significant differences (p <0.05) among the treatments for: pH, DO, hardness and alkalinity. Regarding the growth variables, significant differences (p <0.05) were observed, with higher MAD, Y and SGR values for the 10:1 treatment (3,433 ± 267 ind L-1, 245 ± 19 ind L-1 day- 1 and 45.3 ± 0.6% day-1, respectively) and lower for the 20:1 (1,011 ± 283 ind L-1, 55 ± 15 ind L-1 day-1 and 28.3 ± 1.6% day-1, respectively). The MDD occurred on day 12 for the 10:1 treatment and on day 18 for the 15:1 and 20:1 treatments. Alkalinity and hardness had stronger influence on the growth variables, which was also indicated by the simple linear regression. The principal component analysis (PCA), with 80% of explanation, identified high values of SGR, density and Y for the 10:1 and high values of alkalinity, hardness, DT and NO2 for the 20:1. Thus, the use of effluent from Tilapia farming in a biofloc system with a C:N ratio of 10:1 provided better production results for D. magna, demonstrating that it is an option for the production of live feed for aquaculture.

Effects of elephant's foot (Elephantopus scaber) extract on growth performance, immune response, and disease resistance of nile tilapia (Oreochromis niloticus) fingerlings

Medicinal plant has been applied as an alternative strategy for antibiotics and chemotherapeutics for controlling the outbreak of diseases in tilapia farming. In this study, five doses of Elephantopus scaber extract (ESE) were added to the basal diet at 0, 2.5, 5, 10, and 20 g kg−1 feed of Nile tilapia fingerlings (13.92 ± 0.06 g initial weight) in triplicate. After 4- and 8- weeks post-feeding, fish were sampled to determine the effects of the ESE supplemented on fish's growth performance, humoral, and skin mucus immune response. After 8 weeks post-feeding, a challenge test against Streptococcus agalactiae was carried out using 10 fish from each tank. Fish fed ESE showed significantly increased serum lysozyme (SL), serum peroxidase (SP), alternative complement (ACH50), phagocytosis (PI), and respiratory burst (RB) compared to the control group (P < 0.05). The skin mucus lysozyme (SMLA) and skin peroxidase (SMPA) were stimulated in fish fed ESE diets. Dietary inclusion of ESE significantly (P < 0.05) promoted final body weight (FW), weight gain (WG), and specific growth rate (SGR); while a reduction in feed conversion ratio (FCR) was observed in fish fed 5 g kg−1 ESE, after 8 weeks post-feeding. The challenge study indicated that the relative percent survival (RSP) was 38.10%, 76.19%, 66.67%, and 47.62% in Diet 2, Diet 3, Diet 4, and Diet 5, respectively. Among the supplemented groups, dietary of 5 g kg−1 ESE showed significantly higher RPS and the highest resistance to S. agalactiae in comparison with other groups. In conclusion, supplementation of ESE (5 g kg−1) enhanced the humoral and mucosal immunity, promoted growth performance, and improved disease resistance of Nile tilapia against Streptococcus agalactiae.

Cage aquaculture in Neotropical waters promotes attraction and aggregation of fish

The influence of cage aquaculture on the attraction and aggregation of wild fish was evaluated with an experimental tilapia farming structure. The structure was installed in the Corvo River, Rosana Reservoir, Paranapanema River basin, for 140 days. Samples were taken before and after farming began. Gillnets on the surface and near the bottom at different distances from the cages (0, 100 and 400 m) were used for fish sampling. The effects of the food supply at two protein levels were also analysed: Phase 1 = 32% PB and Phase 2 = 28% PB. Changes in species richness and abundance were observed, with the number of individuals and the fish biomass increasing significantly just after the farming began. Some species, such as Iheringichthys labrosus, presented increased abundance near the cages, while others, such as Plagioscion squamosissimus, were more abundant far from the cages. Auchenipterus osteomystax was the most abundant species during the experiment, especially when the protein content of the pellets was higher. It was demonstrated that farming tilapia in cages profoundly altered the abundance and composition of the wild ichthyofauna, suggesting the need to propose effective regulations for such activities, including fisheries restrictions in farmed areas or even the prohibition of cage farming.

Dietary supplementation with Bacillus subtilis LT3‐1 enhance the growth, immunity and disease resistance against Streptococcus agalactiae infection in genetically improved farmed tilapia, Oreochromis niloticus

A feeding trial was conducted to investigate the effect of different levels of Bacillus subtilis LT3‐1 in diets on growth, immune parameters, intestinal morphology and disease resistance in genetically improved farmed tilapia, Oreochromis niloticus. Fish (46.91 ± 0.17 g) were fed with a basal diet supplemented with B. subtilis LT3‐1 at 0 (B0), 3.8 × 10¹⁰ (B1), 7.6 × 10¹⁰ (B2), 1.14 × 10¹¹ (B3) and 1.52 × 10¹¹ (B4) CFU kg⁻¹ for 6 weeks. The results showed that the weight gain of fish in B1 group was significantly enhanced compared to that in B0 group (p < 0.05). The addition of B. subtilis significantly affected serum biochemical indices (total protein, albumin, aspartate aminotransferase, alkaline phosphatase). Besides, the haematocrit, total counts of red and white blood cells, as well as the serum catalase and lysozyme activities, were increased, whereas the serum malondialdehyde, the serum immunoglobulin M and complement three contents were reduced. Parameters for intestinal morphology suggested a healthier intestine for the fish fed B. subtilis‐supplemented diets than fish fed the control diet. The survival rate after Streptococcus agalactiae challenge increased in tilapia fed with B. subtilis. The present study demonstrated B. subtilis can effectively improve growth, immunological status and resistance against S. agalactiae infection in tilapia farming.

Backyard farming of tilapia using a biofloc-based culture system

Backyard farming of tilapia using a biofloc-based culture system

Molecular typing of Streptococcus agalactiae isolates of serotype Ia from tilapia in southern China.

Streptococcus agalactiae is an important pathogen of tilapia causing enormous economic losses worldwide. In this study, multilocus sequence typing indicated that 75 S. agalactiae isolates from tilapia in southern China belonged to sequence type-7, as well as belonging to serotype Ia, as confirmed by multiplex PCR assay. The putative-virulence gene profiles and genetic variation of these strains were determined by three sets of multiplex PCR and multi-virulence locus sequencing typing (MVLST), respectively. Analysis of putative-virulence gene profiles showed that each strain harbored 18 putative-virulence genes but lacked lmb and scpB. Three putative-virulence genes (srr-1, bibA and fbsA) were further selected for MVLST analysis. Our data showed that the strains had 14 MVLST types (1-14) and clustered in three groups (Groups I-Ⅲ). The period of time during 2013 and 2014 was an important turning point for the differentiation of the putative-virulence genes of S. agalactiae, as type 1 within Group Ⅱ became the predominant MVLST type. There were significant differences in MVLST types of S. agalactiae isolated from different tilapia farming regions. MVLST assay may improve the discriminatory power and is suitable for understanding the epidemiology of S. agalactiae serotype Ia and screening multivalent vaccine candidate strains.

Variability of the nitrifying bacteria in the biofilm and water column of a recirculating aquaculture system for tilapia ( Oreochromis niloticus ) production

The aim of this study was to evaluate variability of nitrifying bacterial community in the biofilm and in the water of a recirculating aquaculture systems (RAS) in a tilapia farming in order to determine if nitrification process is dependent, or not, of nitrifying bacteria abundance. Biofilm and water samples were collected periodically for 30 days and analysed with the fluorescent in situ hybridization (FISH) technique, used to quantify ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB). Ammonia presented the peak in the first week, while the nitrite's maximum was recorded in the second week. Nitrate increased steadily, indicating nitrification activity. Total bacterial abundance in biofilm increased continuously, while in water, it did not change significantly. In the biofilm, number of AOB was high at beginning, decreased after few days and increased again following augment of ammonia. Number of NOB also showed an increase in abundance in biofilm following the increment of nitrite and nitrate. In water, AOB and NOB did not show major variability. Relative abundance of nitrifying bacteria represented more than 30% of total bacteria in biofilm at beginning of the experiment. Their contribution decreased to >3% in last days. It indicates that nitrifying bacteria are biofilm colonizers, and that their activity seems to be directly related to the concentration of nitrogen compounds. However, contribution of nitrifying bacteria did not vary much along the time. We may conclude that the biofilm-nitrifying bacteria plays major role in nitrification process in RAS and that the activity of these organisms is dependent of their abundance in response to the concentration of nitrogen compounds.

Effects of temperature changes in the transcriptional profile of the emerging fish pathogen Francisella noatunensis subsp. orientalis

One of the major challenges in Nile tilapia (Oreochromis niloticus L.) farming is the occurrence of bacterial infections, and the Francisella noatunensis subsp. orientalis (FNO) is an important pathogen that has emerged in last decades. Francisellosis outbreaks have been reported in the literature as occurring seasonally when water temperature is below 24 °C. The aim of this study was to quantify the median lethal doses (LD50) of FNO in experimental challenges at 28 °C and 22 °C, and to investigate the impact of temperature changes in whole genome expression using microarray technology. The LD50 for Nile tilapia at 28 °C was ∼105.7, whereas at 22 °C, the LD50 was ∼102.2, showing that the decrease in temperature enhanced disease outcome. Out of 1917 genes screened, a total of 31 and 19 genes were down- and up-regulated at 22 °C, respectively. These genes were grouped by orthology into functional categories of: amino acid, inorganic ion, and carbohydrate transport and metabolism; transcription; and posttranslational modification, protein turnover, and chaperones. Expression of genes related to metabolism, oxidative stress, and thermal shock were regulated by temperature changes, reflecting an ability of FNO to adapt to the environment. Expression of virulence genes usually required for the Francisella genus was not changed between tested temperatures, including that of genes located on the Francisella Pathogenicity Island.