Koi pond moss outbreak and dead fish incident full-dimension disposal program

I. Pathologic analysis of moss outbreaks and dead fish correlations

1. Ecological threat of moss overpopulation
   • Dissolved oxygen competition: nighttime respiration of moss consumes dissolved oxygen in the water column (<3mg/L when koi asphyxiate)
   • Toxin release: Hydroxylamine is produced from the decomposition of dead moss (concentration >0.05mg/L can cause gill filament necrosis)
   • Mechanical Damage: filamentous algae entangles fish body resulting in dislodging of mucus from the body surface (increased probability of infection by 801 TP3T)
2. Triple chain of causation for spring fish kills
   

   hierarchy of causal factors	concrete expression	threshold value
   Class I risk (direct mortality)	Acute hypoxia, gill parasite outbreaks	DO＜1.5mg/L
   Secondary risk (chronic impairment)	Ammonia nitrogen poisoning, enteritis complications	NH3＞0.02mg/L
   Level 3 risk (system crash)	Disintegration of the nitrification system, exponential growth of pathogenic bacteria	ORP＜200mV

II. Rapid moss removal and ecological restoration program

(i) Physical Intervention Technology Group

1. UV Quantum Algaecide System
   • Upgrade UV lamp to 10W/ton water standard, quartz casing transmittance needs to be >85% (weekly alcohol wipe)
   • Adoption of the "vortex sterilization chamber" design, which creates a spiral trajectory of the water flow (the irradiation time is extended to 12 seconds).
2. Mechanical scraping specifications
   • Use a 304 stainless steel scraper (blade angle 30°) to work at an angle of 45° along the pool wall.
   • Daily 09:00 - 11:00 focused cleanup (avoiding the peak of morning fish feeding)

(ii) Chemical Modulation Technical Group

1. Precision application of moss cleaner
   • Sodium humate (200g/ton) + Bacillus subtilis (20g/ton) mixed sprinkling
   • Turn on protein separator after dosing (≥10% pool water per hour)
2. Emergency Algae Killing Program
   

   Type of agent	Conditions of use	Operating Points
   borax	PH < 7.5	0.7ppm whole pool splash (water change within 24 hours 30%)
   potassium bisulfate	When fry are present	0.3ppm salt complex (with VC Stress)

(iii) Technical Group on Biological Inhibition

1. Targeted cultivation of algae-suppressing flora
   • Volcanic rock (particle size 3-5cm) + mafic rock (particle size 2-3cm) composite filter bed in the filter bin.
   • Biofilm activation by weekly dosage of EM bacterial solution (50ml/ton).
2. ecological competition regulation
   • Introduction of Chlorella species (500ml/ton) to compete with moss for nutrients
   • Sprinkle potassium dihydrogen phosphate (0.2 ppm) to regulate N/P ratio

III. In-depth disposal process for dead fish incidents

(i) The golden 6 hours of diagnostic pathology

1. Rapid on-site testing
   • Multi-point detection using a portable dissolved oxygen meter (error ±0.1mg/L)
   • Take gill filament samples for microscopic examination: find fingerlings >3/field of view and isolate immediately
2. autopsy and diagnosis
   

   Inspection area	pathological characteristics	Direction of disposal
   gills	Pale mucus is plentiful	Acanthamoeba infection
   intestinal tract	jejunal congestion	enteritis septicaemia
   liver disease	Earthy yellow and brittle	ammonia nitrogen poisoning

(ii) Three-tier emergency response system

1. Level 1 response (<2 hours)
   • Turn on the emergency oxygenation system (air pump power increased to 5W/m2)
   • Splash calcium peroxide (0.5ppm) in the whole pool to improve dissolved oxygen.
2. Secondary disposal (2-24 hours)
   • Diseased fish 0.51 TP3T saline bath (with 0.2 ppm povidone iodine)
   • Healthy fish fed allicin bait (add 1.5%)
3. Tertiary repair (24-72 hours)
   • Re-establishment of nitrification system: placement of freeze-dried powder of nitrifying bacteria (100g/ton)
   • Progressive water change (daily water change ≤ 15%)

IV. Construction of a long-term prevention and control system

1. Water Quality Monitoring Internet of Things
   • Deployment of multi-parameter sensors (quadruple monitoring of ORP, NH3, DO, PH)
   • Setting alarm threshold: NH3＞0.01mg/L automatically start protein separation
2. Ecological buffer zone construction
   • Planting calamus around the pool (density 3 plants/m2) to absorb excess nutrients.
   • Installation of surface floating islands (coverage 15%-20%) to suppress light
3. Annual maintenance nodes
   March: cleaning of filter system (retain 1/3 of old filter media)

   June: Testing of UV lamp radiation intensity (<280nm needs to be replaced)

   November: reinforcement of pool insulation (water temperature fluctuations <2°C/day)

V. Fifteen years of special warnings for players

1. Three fatal operational taboos
   • Chlorine dioxide prohibited during moss outbreaks (exacerbates hypoxia)
   • Prohibit water changes when water temperature changes suddenly (temperature difference >3℃ induces stress)
   • Ban broad-spectrum antibiotics until diagnosis is confirmed (disrupts microecology)
2. Equipment redundancy configuration standards
   

   System type	redundancy	Switching Response Time
   oxygen delivery system	200%	<30 seconds
   circulatory system	150%	<5 minutes
   Sterilization systems	120%	<10 minutes

Summary: moss management should follow the principle of "inhibiting algae and cultivating bacteria", through the upgrading of the ultraviolet system, optimization of biological filter beds and dynamic monitoring of dissolved oxygen. 2 Build a three-dimensional prevention and control system. The disposal of dead fish needs to grasp the principle of "quick diagnosis and quick treatment", and establish a pathology database to assist decision-making. It is recommended to configure automatic dosing system (error ± 5%) to realize precise prevention and control, and control the annual mortality rate below 0.5%.