Xenotoca doadrioi

Xenotoca doadrioi

Advanced scientific guide to long‑term care, conservation breeding, and colony management.

Goodeidae • Goodeinae CR • Critically Endangered (micro‑endemic) Cool, hard, highly oxygenated water

Taxonomy & evolutionary context

Order: Cyprinodontiformes
Family: Goodeidae
Subfamily: Goodeinae
Species: Xenotoca doadrioi

Formerly grouped under Xenotoca eiseni, this species is now recognised as a distinct lineage based on mitochondrial and nuclear markers, male pigmentation, and its restricted distribution in the Río Tamazula basin. For conservation work, line integrity and locality data should be preserved wherever possible.

Native habitat & environmental physiology

Hydrology

  • Shallow, clear tributaries with moderate–high flow.
  • Gravel and cobble substrate with leaf litter and periphyton.
  • Seasonal variation; dry‑season pools persist.

Water chemistry (wild)

  • pH 7.6–8.3; GH 12–20 dGH; KH 8–14 dKH.
  • Conductivity ~450–650 µS/cm.
  • Temperature 18–24°C with cool nights.

Agricultural runoff, invasive poeciliids, and hydrological instability are major pressures. Captive conditions should prioritise high oxygenation, stable mineral content, and cooler temperatures to mirror this ecology.

Optimised captive water parameters

Parameter Target range Rationale
Temperature 19–22°C Mimics cool native regime; reduces metabolic stress.
pH 7.6–8.2 Matches carbonate‑rich habitat.
GH 14–20 dGH Supports robust osmoregulation.
KH 8–12 dKH Prevents pH swings; buffering capacity.
Dissolved oxygen > 8.0 mg/L Rheophilic species; high DO is critical.
Flow Moderate laminar Replicates natural microhabitats.

Avoid sustained temperatures above 24°C: aggression increases, fry survival drops, and chronic stress markers become evident over time.

Nutrition & digestive biology

Goodeids possess a relatively short, muscular intestine adapted for omnivory with a strong periphyton and plant component. Diets should reflect this, avoiding overly rich carnivore formulations.

Daily base diet

  • Spirulina‑rich flake as primary staple.
  • High‑fibre micro‑pellets (0.5–1 mm).
  • Algae wafers and blanched greens (spinach, kale, dandelion).

Conditioning foods

  • Live daphnia and grindal worms.
  • Frozen mosquito larvae.
  • Newly hatched Artemia (sparingly).

Avoid

  • Heavy bloodworm use (fatty liver risk).
  • Tubifex and similar high‑risk worms.
  • Very high‑protein carnivore pellets.

Reproductive biology & breeding protocol

Key traits

  • Matrotrophic livebearer with trophotaenia.
  • Gestation ~55–65 days.
  • Broods of 5–15 large, robust fry.
  • Sexual maturity at ~4–6 months.

Breeding setup

  • Colony tank 120–150 L.
  • Ratio ~1 male : 3–5 females.
  • Strong oxygenation and moderate flow.
  • Dense planting + rockwork for refuge.
Genetic management: maintain at least two lines (A/B) with periodic male exchange, avoid sibling pairings, and aim for an effective population size (Ne) of ≥ 20 per line to reduce inbreeding.

Fry rearing protocol

0–48 hours

  • No feeding; yolk reserves sufficient.
  • Maintain DO > 8 mg/L; zero ammonia.
  • Gentle flow; no strong surface agitation directly on fry.

Days 3–14

  • Crushed spirulina flake 2–3× daily.
  • Baby brine shrimp 1–2× daily.
  • Daily 20–30% water changes with matched parameters.

Days 14–60

  • Introduce grazing stones with algae/biofilm.
  • Increase plant matter in diet.
  • Maintain cooler temps (19–21°C) for optimal growth.
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