| 1. System Architecture & Engineering Requirements |
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| System Type | Dedicated syngnathid RAS (Recirculating Aquaculture System) with independent broodstock, gestation, and larval modules. |
| Hydrodynamic Profile | Laminar–dominant flow regime (Re < 2000) with micro‑eddy zones for holdfast stability; avoid turbulent shear > 0.4 N·m⁻². |
| Turnover Rate | Broodstock: 6–8×/h; Larval: 10–12×/h with diffused return manifolds. |
| Biofiltration | Dual‑stage: MBBR (K1/K3 media) + high‑surface‑area ceramic blocks; nitrification capacity ≥ 0.8 g TAN/m²/day. |
| Gas Exchange | Degassing tower + oxygen cone; maintain DO 95–100% saturation without microbubble entrainment. |
| 2. Water Chemistry Stability & Control Systems |
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| Temperature | 25–26°C with ±0.2°C stability (PID‑controlled titanium heaters + chiller redundancy). |
| Salinity | 32–34 ppt with automated top‑off; conductivity drift < 0.5 ppt/day. |
| pH Control | 8.0–8.3 via CO₂ stripping + automated alkalinity dosing (carbonate buffer). |
| ORP | 300–330 mV; ozone injection upstream of carbon reactor to prevent oxidative stress. |
| Microbial Load | Target heterotrophic bacteria < 1×10⁵ CFU/mL; UV sterilisation at 180–220 mJ/cm². |
| 3. Broodstock System Design |
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| Tank Geometry | Vertical‑biased tanks (60–90 cm height) to support rising courtship behaviour. |
| Flow Pattern | Directional laminar flow with velocity 1–3 cm/s; avoid vertical jets. |
| Holdfast Engineering | Artificial gorgonians, vertical rods, and chain structures with 0.5–1.5 cm diameter for optimal tail grip force. |
| Lighting | PAR 40–80 µmol/m²/s; 12–14 h photoperiod; spectral bias toward 450–500 nm to enhance courtship signalling. |
| Biosecurity | Broodstock module isolated from larval module; independent filtration loops; footbath + tool sterilisation SOPs. |
| 4. Broodstock Conditioning (Nutritional Engineering) |
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| Diet Composition | HUFA‑enriched mysis (DHA ≥ 20 mg/g dry weight), copepods, enriched Artemia; carotenoid supplementation (astaxanthin 50–100 ppm). |
| Feeding Frequency | 3–4× daily; automated micro‑portion feeders recommended. |
| Energy Budget | Target FCR 4.5–6.0; broodstock require 2–3× maintenance energy due to male pregnancy costs. |
| Condition Metrics | Brood pouch vascularisation score; hepatosomatic index; snout‑to‑tail condition factor. |
| 5. Courtship, Mating & System‑Level Synchronisation |
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| Environmental Synchronisation | Stable photoperiod + dawn ramping (10–15 min) to trigger morning courtship. |
| Flow Synchronisation | Reduce flow by 20% during peak courtship window to stabilise rising behaviour. |
| Pair Stability | Maintain visual but not physical separation during acclimation to reduce mispairing. |
| Failure Modes | High flow → failed egg transfer; low DO → reduced pouch pumping; poor enrichment → embryonic resorption. |
| 6. Male Pregnancy Management |
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| Gestation Length | 14–21 days at 25–26°C. |
| Pouch Physiology | Osmoregulatory microenvironment; ionocyte‑rich epithelium; controlled salinity ramping for embryo acclimation. |
| Monitoring | Daily pouch volume index; behavioural metrics (pouch pumping frequency, feeding rate). |
| Critical Risks | Pouch emphysema (gas supersaturation), bacterial pouchitis, premature parturition under stress. |
| 7. Parturition Engineering & Neonate Capture |
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| Parturition Timing | Typically 04:00–09:00; triggered by circadian entrainment. |
| Capture System | Overflow‑fed larval collector with 200–300 µm mesh; zero‑suction design. |
| Lighting | Sub‑1 lux red light to avoid startling male during contractions. |
| Failure Modes | Surface‑tension trapping; air ingestion; mechanical injury from pump intakes. |
| 8. Larval Rearing System (Hydrodynamic Engineering) |
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| Tank Type | Kreisel or pseudo‑kreisel with circular flow; radius of curvature ≥ 20 cm. |
| Flow Velocity | 0.5–1.2 cm/s; avoid shear zones > 0.3 N·m⁻². |
| Water Depth | 30–40 cm to reduce surface‑tension mortality. |
| Aeration | Fine diffusers; bubble size < 1 mm; avoid microbubble entrainment (risk of gas embolism). |
| Side‑Blackout | Black walls to reduce wall‑strikes and improve prey contrast. |
| 9. Live‑Feed Engineering & Nutritional Biochemistry |
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| Primary Feed | Enriched Artemia nauplii (DHA 20–30 mg/g; EPA 10–15 mg/g). |
| Enrichment Protocol | 12–24 h enrichment with microalgae + HUFA emulsion; target DHA:EPA ratio 2:1. |
| Prey Density | 5–10 nauplii/mL; constant background density via drip‑feed live‑feed reactor. |
| Copepod Integration | Acartia tonsa nauplii improve survival by 20–40% due to superior fatty acid profile. |
| 10. Larval Development & System‑Level Constraints |
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| Week 1 | Critical mortality window; optimise prey density, flow, and DO; avoid surface‑tension traps. |
| Week 2–3 | Improved swimming; early hitching; introduce micro‑holdfasts. |
| Week 3–6 | Weaning to chopped mysis + micro‑pellets; maintain some live feeds. |
| Failure Modes | Bacterial blooms, poor enrichment, hydrodynamic dead zones, microbubble embolism. |
| 11. Quantitative Survival Modelling |
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| Expected Survival | 20–50% to 6 weeks under optimised engineering conditions. |
| Key Predictors | Prey density variance, DO stability, enrichment quality, flow uniformity index. |
| Mathematical Model | Survival S(t) ≈ e^(−(α·σ²_flow + β·ΔDO + γ·prey_var + δ·bacterial_load)). |
| Scaling | Linear scaling limited by live‑feed production; exponential scaling limited by biosecurity. |
