Min Eun Young Diagnosis of Fish Disease 5 SunMoon University Aquatic Life Medicine

Diagnosis of Fish Disease  Water quality - The single, most important factor affecting fish health and influencing disease in fish ponds and tanks is water quality. 1. Component of water 1) Major ions: sodium, potassium, magnesium, calcium, sulfates, chlorides and hydrogen carbonate ( 탄산수소염 ) 2) Key nutrient ions: phosphates (P) and nitrate (N) → algae growth 3) Dissolved gasses: O 2, CO 2, N 2, H 2 SO 4 4) Trace ions: copper, iron, zinc, fluoride, cobalt and molybdenum which are important in minute amount, but can be toxic to fish at higher levels

Diagnosis of Fish Disease  Water quality 2. What do fish want? Not clarity 1) Low ammonia & nitrite: NH 3, NO 2, N 2 etc 2) Chemically clean water 3) Water hardness, pH & temperature - Hardness ( 경도 ): a measurement of the concentration of divalent metal ions such as calcium, magnesium, iron, zinc etc. - In most water, it consist mainly of calcium and magnesium salts, with trace amounts of other metals 4) Low levels of organic pollution 5) Stability not fluctuation: constant changes → stress Ex) pH, temp etc

Diagnosis of Fish Disease  Water quality 3. Important factors 1) Ammonia (1) The effects on fish health ① At low levels ( <0.1 mg/L NH 3 ), 0.1ppm 도 자극적 ② Fish response to sub-lethal levels are similar to those to any other form of irritation → flashing & rubbing against solid objects Cf) 기생충 감염과 유사한 행동 : 급격한 유영 및 수조에 몸을 비벼 됨 → 어류가 위와 같은 증상을 보이면 기생충 검사와 수질 검사 동시 실시 ③ Prolonged exposure to sub-lethal levels can lead to skin and gill hyperplasia ( 과형성, 증생 ) → 호흡곤란hyperplasia ④ At higher levels ( >0.1 mg/L NH 3 ) even relatively short exposure can lead to skin, eye and gills damage. Elevated levels can also lead to ammonia poisoning by suppressing normal ammonia excretion from the gills. → 삼투 압 파괴, 혈액 내 암모니아 농도 증가 → 호흡곤란

Diagnosis of Fish Disease  Water quality 3. Important factors 1) Ammonia (1) The effects on fish health ⑤ The fish response to toxic levels would be lethargy ( 무기력 ), loss of appetite ( 식욕부진 ), laying on the pond bottom with clamped fins, or gasping at the water surface in the gills have been affected ( 헐떡거림 ). (2) The chemistry of ammonia ① In water: NH 3 + H 2 O ↔ NH OH - ② The quantity of each species is dependent on both pH & temp. ③ pH ↑ → NH3 ↑, pH ↓ → NH 4 + 새벽녘에는 pH ↓, 온도 ↑ → NH 3 ↑ (3) The toxicity of ammonia ① All test kits measure total ammonia-nitrogen (TAN: NH 3 + NH 4 + ) ② Above 0.1 mg/L TAN should be considered as unacceptable and steps taken to reduce it (Table 3. tolerance limit of TAN)Table 3. tolerance limit of TAN

Diagnosis of Fish Disease  Gill Hyperplasia ( 과형성, 증생 ) Normal gill lamella Gill lamella fusionGill lamella epithelial cell hyperplasia ←Back

Diagnosis of Fish Disease Tolerances of Ammonia concentration  Tolerances of Ammonia concentration pH Temperature ( ℃ ) (4) Reducing ammonia levels ① Partial water changes ( 환수 ) ② Reduce or stop feeding ( 절식 ) ③ Using zeolite ( 여과 ) ④ Acceptable level not zero levels: nitrifying bacterial (nitrobacteria) survival need ⑤ Weekly testing should be done

Diagnosis of Fish Disease  Water quality 3. Important factors 2) Nitrite (NO 2 - ) (1) General comments ① Although it is less toxic than ammonia, elevated levels still present a threat to fish health. ② Prolonged exposure to low levels can lead to stress and is often associated with stress-related disease as bacterial ulcers and fin-rot. ③ 2NH 3 + 3O 2 → 2NO H+ + 2H 2 O : nitrosomonas ( 아질산화 ) 2NO O 2 → 2NO 3 - : nitrobacter ( 질산화 ) ④ NO 3 + 유기물 → CO 2 + N 2 + H 2 O + OH - Denitrification bacteria: pseudomonas, micrococcus, achromobacter, bacillus ⑤ Nitrate (NO - ) is consider less toxic than nitrite (NO 2- ) ⑥ At higher levels, skin & gill epithelial cell can be damaged and opportunistic bacteria and parasites may take advantage of stressed fish

Diagnosis of Fish Disease  Water quality 3. Important factors 2) Nitrite (NO 2 - ) (2) Signs ① At low levels: may rub against solid objects or flash ② As levels increase the fish will become lethargic ( 무기력 ), but may still swim up to feed. ③ If the fish is suffering from nitrite (NO - ) poisoning, the gill will be pale than to dark brown in color and the fish may exhibit signs of respiratory distress. (3) Control ① Partial water changes until levels stabilize ② Adding 8g of salt/ L, along with regular water changes : chloride 가 gill 에 nitrite 보다 더 잘 붙어서 아질산 중독을 피할 수 있다. ③ Aeration should also be increased. (4) New pond or tank syndrome

Diagnosis of Fish Disease  Water quality 3. Important factors (4) New pond or tank syndrome ① Elevated Nitrite (NO 2 - ) levels are common ② As the ammonia levels start to stabilize, it would be expected to see an increase in nitrite levels which in turn has to be managed until the nitrobactor bacteria that process nitrite become fully established. ③ NH 4 -N → nitrosomonas → NO 2 -N → nitrobactor → NO 3 -N 탈질화 반응 ( 무산소 상태 ) ④ 탈질화 세균 : micrococcus, achromobacter, psedumononas, bacilius ⑤ NO 3 -N 이 어체 내에서 hemoglobin 과 결합 → methemoglobin ( 청색증 ) ⑥ Circulation of nitrogen (N)N

Diagnosis of Fish Disease  Water quality 질소 형태의 변화과정 Nitrosomonas 작용 Nitrobactor 작용 → 암모니아 농도가 안정적이 되어야 nitrobactor 활동

Diagnosis of Fish Disease  Water quality 3. Important factors 3) Organic toxicants : Parathion, Toxaphene, Malathion, TFM, Dichlobenil, Sodium arsenite, Endothal, Trichlorofon, (Dylox) Mirex, Endrin, Methoxychlor 2,4- hydrothol - Alkyl benzene sulfonate, Phenol, ABS (A detergent) - Organic solvents/ Wood-fiber wastes : Hydrogen sulfide, Dimethy sulfoxide 4) Inorganic toxicants : mainly heavy metals 5) Gases ① Nitrogen gases ② Gas bubble disease : gas-bubble in branchial arterioles as gas emboliGas bubble disease

Diagnosis of Fish Disease  Water quality Gas bubble disease

Diagnosis of Fish Disease  Water quality 3. Important factors 6) pH ① Water hardness are stabilized. ② Soft water ( 연수 ): slightly acidic, poorly buffer ③ Hard water ( 경수 ): alkaline, well buffer → 연수보다 경수가 pH 의 변화가 적다 ④ Hardness ( 경도 ): 물의 세기, 2 가 이온 (Fe, Mn, Ca, Mg, Sr) ⑤ Morning: pH ↑ - 호흡으로 인한 CO 2 증가로 인함 Evening: pH ↓ - 낮 동안의 광합성으로 인해서 O 2 증가로 인함 7) Water temperature ① Affect the solubility of oxygen in water Cf) summer ② The oxygen requirement increase as water temp. increase ③ Affect immune system, wound healing, digestion ④ For most cold water fish, the immune response is severely inhibited below 12 ℃ Ex) salmon

Diagnosis of Fish Disease  Water quality 3. Important factors 7) Water temp. ⑤ Temp ↓: bacterial activity ↓, fish immune response ↓ Temp ↑: bacterial activity ↑, fish immune response ↑ (limit as fish) ⑥ Importance of water temp. balance