CHAPTER ONE 1.0 INTRODUCTION1.1 Fish Fishas defined by Merriam-Webster is any of numerous cold-blooded strictly aquatic craniatevertebrates that include the bony fishes and usually the cartilaginousand jawless fishes and that have typically an elongated somewhat spindle-shapedbody terminating in a broad caudal fin, limbs in the form of fins when presentat all, and a 2-chambered heart by which blood is sent through thoracicgills to be oxygenated.
Therole of fish as an important source of food, income, employment, as well asrecreation for people around the world cannot be underemphasized. Also, fish isknown as a very paramount source of animal protein for both man and livestockin developed and developing countries. Nigeriaas a developing country has a current demand for fish to be about four timesthe level of local production. Humans consume approximately 80 percent of thecatch as food. The remaining 20 percent goes into the manufacturing of productssuch as fish oil, fertilizers, and animal food (Ozigbo et al.
, 2014). 1.2 Fisheries and AquacultureFisheriesand aquaculture are integral parts of agriculture which were found to have thecapacity to increase the country’s GDP (Gross Domestic Product) and can solvethe unemployment problem for our teeming youths if adequately managed (Ozigbo et al., 2014).Aquacultureis an embodiment of the overall agricultural production system in Nigeria.
Themajor species cultured in Nigeria include tilapias, catfish and carp; howeverthe African catfish Clarias gariepinus is the most farmed (Agbede etal., 2003).Clarias gariepinusis one of the most resistant and widely accepted and highly valued fish thatcould be cultivated in Nigeria, therefore the need for documented research onpathogens which might constitute serious problems on this fish cannot be overemphasized(Dankishiya and Zakari, 2007).Theapplication of medicinal plants in aquaculture is gaining popularity in recentyears. Ngo (2015) highlighted that theapplication of medicinal plants which have been known as immunostimulants forthousands of years as natural and innocuous compounds has potential inaquaculture as an alternative to antibiotics and immunoprophylactics.
Hefurther stressed that the growing interest in these plants has increasedworld-wide because they are easy to prepare, cheap, and have few side effectson animals and the environment.Also, medicinal plants show their mainproperties as growth promoters, immune enhancers, where they act asantibacterial and antiviral agents to the host immune system). This statementis in agreement with the works of Reverter etal (2014) that aquaculture is the main source to increase fish supply. Fastdevelopment of aquaculture and increasing fish demand lead to intensificationof fish culture, magnifying stressors for fish and thus heightening the risk ofdisease. Until now, chemotherapy has been widely used to prevent and treatdisease outbreaks, although use of chemical drugs has multiple negative impactson environment and human health e.g. resistant bacterial strains and residualaccumulation in tissue.
Hence, disease management in aquaculture shouldconcentrate on environmentally friendly and lasting methods. Reverter et al (2014) also emphasized thatrecently, increasing attention is being paid to the use of plant products fordisease control in aquaculture as an alternative to chemical treatments. Plantproducts have been reported to stimulate appetite and promote weight gain, toact as immunostimulant and to have antibacterial and anti-parasitic (virus,protozoans, monogeneans) properties in fish and shellfish aquaculture due toactive molecules such as alkaloids, terpenoids, saponins and flavonoids.Aquacultureis one of the important sectors contributing significantly in the Nigerianeconomy.
For increased production and profit, fish farmers are encouragedtowards intensification of culture system. In such practice of fish/shrimpfarming, disease becomes major problem. Disease is one of the most importantproblems of fish production both in culture system and wild condition ofNigeria. Fishes have been suffering from many diseases such as epizooticulcerative syndrome (EUS), tail and fin rot, fungal, parasitic and bacterialinfections (Chowdhury, 1999). With the outbreak of EUS in 1988, Channa sp.,Puntius sp., Anabas sp., Clarias sp.
, and other indigenousspecies of fish are seriously affected (Barua et al., 1991). Thus toprevent and control of fish diseases, treatment trials has become an essentialcomponent of fish production. Chemotherapyhas progressed internationally for treating the most diversified infectiousdisease of fish (Shieszko, 1959). However, there are problems associated withthe use of such chemicals.
It was the demand of the time to look foralternative means of commercial synthetic drugs. Medicinal plants are vital sourceof drugs from the ancient time holding the scenario of the Indian system ofmedicine (Sharma et. al., 2009).
According to Ghani (1998) medicinalplants are rich sources of bioactive compounds and thus serve as important rawmaterials for drug production. In Bangladesh, different kinds of medicinalherbs are available which grow in roadside, small jungles are fellow lands andmost of them are cultivable with very low cost. The application of herbalmedicine has grown in laboratories and in papers with little field practice.
Some farmers have experienced this treatment method as crude extract of herbs(Ha Thu et al., 2011). It is thus necessary to apply both the crude andfine extract of herbs which can carry more specific and confirm use of herbalmedicine in laboratory and field at large scale. Thus the objective of presentstudy was to observe the use of various medicinal plant products against fishdiseases. 1.3 Medicinal PlantsMedicinalplants have been used as sources of medicine in virtually all cultures (Baquer,1995).
Ithas been estimated that approximately 420,000 plant species exist on earth, butfor most of these, only very limited knowledge is available. Three approaches,which are closely related to diet (foodstuffs), medical practice (folk andtraditional medicines), and scientific research (phytochemical analysis), canbe adopted to explore the value of medicinal plants/herbs. Based on theexperience from random trials and observations in animals, ancient peopleacquired the knowledge of using herbs for treating illness (Samy et al., 2008). Thedrugs of today’s modern society are products of research and development, whoseraw materials are naturally occurring materials which are obtained from plants;either in the roots stems, leaves, fruits and seeds (Odugbemi and Akinsulire,2006; Burkill, 1994).TheWorld Health Organization (WHO) has pointed out that traditional medicine is animportant contribution to its health goals.
There are considerable economicbenefits in the development of indigenous medicine and in the use of medicinalplants for the treatment of various diseases (WHO, 2003).Medicinalplants have also been of importance in the health care system of localcommunities as the main source of medicine for the majority of the rural population.Plants have not only nutritional value but also, in the eyes of the localpeople, they have medicinal and ritual or magical values (Adewunmi et al., 2001).Plantshave been a major source of medicine for human kind. According to availableinformation, a total of at least 35,000 plants species are widely used formedicinal purposes.
The demand for traditional herbs is increasing veryrapidly, mainly because of the harmful effects of synthetic chemical drugs. Theglobal clamor for more herbal ingredients creates possibilities for the localcultivation of medicinal and aromatic crops as well as for the regulated andsustainable harvest of wild plants. Such endeavors could help raise ruralemployment in the developing countries, boost commerce around the world andperhaps contribute to the health of millions (Anita, 2004).Nigeriais endowed with an enormous diversity of animals and plants, both domesticatedand wild, and an impressive variety of habitats and ecosystems. This heritagesustains the food, medicinal, clothing, shelter, spiritual, recreational, andother needs of her population (Odugbemi and Akinsulire, 2006).
Plantshave provided the basis for traditional treatment for different types ofdiseases and still offer an enormous potential source of new chemotherapeuticagent (Adewunmi et al., 2001). Thishowever requires extraction of the bioactive molecules of pharmacologicalimportance present following purification and identification procedures as wellas toxicological studies.TheWorld Health Organization (WHO) estimates that herbal medicines provide primaryhealthcare for approximately 3.5 to 4 billion people worldwide, and about 85%of traditional medicine involves the use of plant extracts (Farnsworth, 2002),which may be called “modern herbal medicine.”Plants,which constitute a major component of foodstuffs in humans, have formed thebasis of various traditional medicine systems and folk medicines that have beenpracticed for thousands of years during the course of human history.
Until now,plants/herbs are still highly esteemed all over the world as a rich source oftherapeutic agents for the treatment and prevention of diseases and ailments;at present, more than 35,000 plant species are used for medicinal purposesaround the world (Yirga, 2011). In conventional Western medicine, 50–60% ofpharmaceutical commodities contains natural products or is synthesized fromthem; 10–25% of all prescription drugs contain one or more ingredients derivedfrom plants (Cameron et al., 2005).Medicinalplants have a long history of use in most communities throughout the world. InAfrica, people still consult traditional healers even when being attended to inconventional orthodox clinics. The history of medicinal plants is widelydocumented in various pharmacopoeias; Plantamedica, Napralert, etc, around the world. Unfortunately, little effort hasbeen made in transforming this vast knowledge using simple low costtechnologies.
Apparently, a great number of rich unclassified indigenousknowledge on the therapeutic ability of medicinal plants abounds in Africa thathas not been documented for possible modification and application by academiato address the pressing problems of indigenous people on the African continent.Mostplant parts (extract) identified such as (bark, roots, seeds, fruit and leaves) serve as major source of activeingredient and products of secondary metabolites such as alkaloid, terpenoids etcused in curing diseases, production of drugs as well as in maintaining goodhealth by both the traditional and orthodox medical practitioners (Nwachukwu et al., 2010).Cowan(1999) revealed that finding healing powers in plants is an ancient idea.People on all continents have long applied poultices and imbibed infusions ofhundreds, if not thousands, of indigenous plants, dating back to prehistory.Evans(2005) highlighted that traditional medicine sometimes called herbalism is themost ancient method of curing diseases. It has been known that plants are thefirst and only true medicines ever used by man (Ariza et al., 2011).
However, in Nigeria, until recently, the practicesof the use of herbs has been kept by secrecy and shrouded in dreaded magicalincantations, rituals and sacrifices. It is now very clear that the potency ofthe plants and its parts does not depend on such exhibition.Theuse of plants for medical purposes is an important part of the culture andtradition in Africa. The number of resistant strains of microbial pathogens isgrowing since penicillin resistance and multi-resistance pneumococci caused amajor problem in South Africa in 1977 (Eloff, 1998; Marchese and Shito, 2001).The development of resistance of antimicrobial agent has forced scientists tosearch for antibacterial substance from alternative sources such as medicinalplants. This has also made medicinal plants to receive much attention as analternative therapy as against synthetic drugs. Traditionally, extracts of Theobroma cacao (Cocoa) have been usedagainst Salmonellae (Busta and Speck,1968) and against Escherichia coli(Ariza et al., 2011).
Arizaet al (2011) also addressed thatattempts to discover non-conventional antimicrobial agents with higheffectiveness and lower toxicity, have put great concern to plant extracts. Phytochemicalcompounds have been extensively studied to perform antibacterial and antifungalactivities. Extract of grape, turmeric and tea leaves have been demonstrated ontheir antibacterial potency against various human pathogens (Sebai et al.,2010; Zhang et al., 2010; Cui et al., 2012; Kawamoto et al.,2012).Different herbal plants orcombinations of them are known to have properties such as anti-stress, growthpromoters, appetisers, tonic and immuno-stimulants.
Moreover, these substancesalso possess other valuable properties; they are non-biodegradable andbiocompatible. No herbal-resistance immunity has been found by any pathogentill today. Some of these herbs and herbal plants remedies have potentanti-viral as well as anti bacterial and anti-fungal properties. Someimportant advantages of herbal plants include their plenty availability and arecheap; their action has been proven effectivewith no adverse effect on natural ecosystem; they act as the substitution forfeed and fertilizer in aquaculture; they act as a growth promoter andimmunostimulant; herbal drugs act as a anti bacterial substrate with antimicrobial activity;act as anti-fungal and anti-parasiticagents (Citarasu,2010)).Medicinal plant hasbeen alternatively used to antibiotics in fish health management (Chakrabortyand Chattopadhya, 1998). These herbs are not only safe for consumersbut also widely available throughout Asia and other countries and they alsohave a significant role in aquaculture (Direkbusarakom,2004). Many studies have proved that herbal additives enhanced thegrowth of fishes and also protected from the diseases (Sasmal etal.
, 2005).Variousherbal products such as Hygrophilas pinosa, with Hanias omnifera,Zingiber officinalis, Solanum trilobatum, A. paniculata, Psoraleacorylifolia, Eclipta erecta, Ocimum sacnctum, Picrorhiza kurooa,P. niruri, Tinospora cordifolia, Purified silajit and codliver oil have the characteristics of the growth promotion, anti-stress,immunostimulation and anti-bacterial. This preparation had a good influence inthe Penaeus larvi culture (Citarasu etal., 2002). Livol (IHF 1000) is a commercial herbal growthpromoter which has been found to significantly improve digestion therebyleading to better growth, production and health in cultivable fishes. Theherbals/spices in the diets induce the secretion of the digestive enzyme.
Itwill result in stimulating the appetite and increasing food consumptionand efficiencies. The growth promoter characteristic herbs induce thetranscription and lead to high protein synthesis. Livol (IHF-1000) is a herbalgrowth promoter containing different plant ingredients such as Bohaevia diffusa,Solanum nigrum, Terminaelia arjuna, Colosynth and black salt andhas been found to significantly improve digestion, thereby leading to bettergrowth, production and health in cultivable fishes. Papaya leaf meal contain anenzyme namely papain which increases the protein digestion, food conversionratio, specific growth rate and weight gain in the 16% unsoaked papaya mealdiet fed to P. monodon post-larvae. Herbal growth promoters help toinduce the transcription rate. This process leads to increase RNA, total amino acid, finally increases production of proteinsin the cells.
Herbal drugs act as immunostimulants dueto the active biochemicals such as alkaloids, flavanoids pigments, phenolics,terpenoids, steroids and essential oils. Immunostimulants are substances, whichenhance the non specific defense mechanism and provide resistance againstpathogenic organisms (Citarasu etal., 2002, 2006).Many plant-derived compounds have been found to have non-specificimmuno-stimulating effects in animals, of which more than a dozen have beenevaluated in fish and shrimp (Citarasu etal., 2006; Sakai, 1999).The better performance of haematological, biochemical and immunologicalparameters were found immunostimulant incorporated diet fed to shrimps (Citarasu etal.
, 2006). The best example is the herb Picrorhiza kurroa used as an antistress compound for shrimps.Bacterialorganisms are responsible for the major infectious disease outbreak in fishfarms and these have been on for over the years. Control of fish disease iscurrently based almost entirely on chemotherapy. Anti-bacterial chemotherapyhas been applied in aquaculture for over 50 years (Inglis, 1996).
Antibioticsare also used prophylactically in carp culture at times of year whenhaemorrhagic septicaemia is most likely to occur (Inglis et al., 1994).But habitual use of anti-bacterials can lead to problems with bacterial resistanceand unacceptable residues in aquaculture products and environment. Theresistant bacterial strains could have a negative impact on the therapy of fishdiseases or human diseases and (environment of fish farms (Smith et al.
, 1994).This situation actually brings human to new medical dilemma Muniruzzaman andChowdhury, 2004). However,medicinal plants possess therapeutic properties; exert beneficialpharmacological effects on the animal body, widely available in nature andeco-friendly. A scientific study to investigate the antibacterial activity ofthe medicinal plants, guava (Psidium guajava) against bacteriapathogenic for shrimp was initiated by Direkbusarakom and Aekpanithanpong(1992). Kraus (1995) found that extract of neem fruit, seeds, seed kernel,twigs, stem bark and root have fungicidal and bactericidal properties.Externally garlic (Allium sativum) is used as disinfectant and it isapplied to indolent tumours, ulcerated surface and wounds (Dastur, 1977).Chowdhury et al. (1991) reported that extract obtained from garlic wasalso highly effective against two tested bacteria, A.
hydrophila andP. fluorescens (MIC 0.6 mg/ml). Althoughseveral works have been done on the use of medicinal plants in curing fishdiseases in Nigeria but little works have been done in this aspect with the useof cocoa and its various parts to treat fish diseases.
In view of this, thestudy is aimed at evaluating the in-vitroefficacies of the different parts of cocoa plants on bacterial organismsisolated from catfish and also to evaluate the efficacies of some selectedsynthetic drugs on some pathogens of C.gariepinus. 1.4 Justification for the StudyFishculture in Nigeria has a great potential. However, the country is still unableto bridge the gap in the short fall between total domestic fish production andthe total domestic demand. In Nigeria, total domestic fish production is farless than the total domestic demand. This may be as a result of less fish beingrealized from aquaculture in consequence of diseases of fish which might havereduced the total fish expected as a result of moribund.
1.5 Objectives of the Study1.5.
1 Broad ObjectiveThebroad objective of this study was to evaluate the in vitro antibacterial effects of some cocoa plant parts extracts (Theobroma cacao) and some selectedsynthetic drugs on fish pathogens isolated from African mud catfish, Clarias gariepinus (Burchell, 1822). 1.5.2 Specific ObjectivesThespecific objectives however, were i.
To identify quantitatively, phytochemicalsfrom parts of the cocoa plant. ii. Determine the sensitivity ofantibacterial effects of parts of cocoa, Theobromacacao plant extracts and some selected synthetic drugs on pathogens ofAfrican mud catfish, C. gariepinus. iii. To compare the therapeutic effects ofthe plant parts extracts with the selected synthetic antibiotic as control onpathogens of African mud catfish, C.gariepinus