Stocking plan
Plan a freshwater tank stocking
Set volume, add species with the numbers you actually plan to keep, and get a conservative verdict for the whole stocking — bioload, group size, zone crowding, and multi-species conflicts, not a single pair in isolation. Use the editor first; the planning notes below explain why a pairwise match still needs a tank-level check.
Shared plan · RISKY
Tank volume is below published minima for at least one species — shop size is not adult swimming space. Review supporting points next, then re-run the check.
Primary issue: Tank volume is below published minima for at least one species — shop size is not adult swimming space. Hard conflicts on file (water, pairing, size, or bettas) — resolve red items before fine-tuning decor or food. 3 fish across 3 species in 20L. Shared temperature 22–26°C. Stocking: balanced (load index 13 vs ref 20). 3 high-severity pairing flag(s).
Your stock
Tank volume is below published minima for at least one species — shop size is not adult swimming space. Review supporting points next, then re-run the check.
One or more species profiles are only partially verified or need verification — treat numbers as planning guidance, not guarantees. At least one species has ID or trade-name ambiguity on file — plan for a typical trade example, not every shop label. Elevated risk verdict — we bias toward safety; your reading of specialist sources still matters.
Pair compatibility for any two species · Fish library
Critical problems
- Corydoras Catfish needs about 60L minimum for adult size (~6cm) and normal swimming space — your 20L tank is below that. Shop size is not adult size.
- Harlequin Rasbora needs about 60L minimum for adult size (~5cm) and normal swimming space — your 20L tank is below that. Shop size is not adult size.
- Corydoras Catfish is a schooling/shoaling species — keeping only 1 is a serious welfare risk; aim for at least 6.
- Harlequin Rasbora is a schooling/shoaling species — keeping only 1 is a serious welfare risk; aim for at least 6.
- Malaysian Trumpet Snail + Corydoras Catfish: Malaysian Trumpet Snail + Corydoras Catfish: Tank may be too small. Malaysian Trumpet Snail and Corydoras Catfish together need at least 60 litres. Your tank is 20 litres. Real tanks add variables Fishori cannot model; treat this as a high-risk read, not certainty.
- Malaysian Trumpet Snail + Harlequin Rasbora: Malaysian Trumpet Snail + Harlequin Rasbora: Tank may be too small. Malaysian Trumpet Snail and Harlequin Rasbora together need at least 60 litres. Your tank is 20 litres. Real tanks add variables Fishori cannot model; treat this as a high-risk read, not certainty.
- Corydoras Catfish + Harlequin Rasbora: Corydoras Catfish + Harlequin Rasbora: Tank may be too small. Corydoras Catfish and Harlequin Rasbora together need at least 60 litres. Your tank is 20 litres. Real tanks add variables Fishori cannot model; treat this as a high-risk read, not certainty.
Warnings
- pH overlap is tight — large water changes can swing chemistry outside the safe band.
Water overlap
What every fish can share at the same time
Shared temperature: 22–26°C
Shared pH: 7.0–7.5 (tight overlap)
Shared temperature range for all species: 22–26°C.
Shared pH window: 7.0–7.5.
Stocking pressure
balanced
Load index 13 vs conservative reference 20 for 20L (adult cm × quantity × bioload weight × territory factor).
Swim-zone distribution
Fish-weighted zone use — top 0.0, middle 1.0, bottom 2.0 (relative biomass per level).
Compatibility summary
Species pairing: avoid
critical· other- Malaysian Trumpet Snail + Corydoras Catfish: Malaysian Trumpet Snail + Corydoras Catfish: Tank may be too small. Malaysian Trumpet Snail and Corydoras Catfish together need at least 60 litres. Your tank is 20 litres. Real tanks add variables Fishori cannot model; treat this as a high-risk read, not certainty.
- Malaysian Trumpet Snail + Harlequin Rasbora: Malaysian Trumpet Snail + Harlequin Rasbora: Tank may be too small. Malaysian Trumpet Snail and Harlequin Rasbora together need at least 60 litres. Your tank is 20 litres. Real tanks add variables Fishori cannot model; treat this as a high-risk read, not certainty.
- Corydoras Catfish + Harlequin Rasbora: Corydoras Catfish + Harlequin Rasbora: Tank may be too small. Corydoras Catfish and Harlequin Rasbora together need at least 60 litres. Your tank is 20 litres. Real tanks add variables Fishori cannot model; treat this as a high-risk read, not certainty.
Pairs checked: 3 · RISKY pair flags: 3 · CAUTION: 0
Fix this setup
Grouped by scenario — work through each block in order
Volume & minimum tank
- 1.Increase tank size to at least 60L, or remove Corydoras Catfish from this stocking plan.
- 2.Increase tank size to at least 60L, or remove Harlequin Rasbora from this stocking plan.
Schooling & group sizes
- 1.Add more Corydoras Catfish to reach at least 6 individuals, or remove the species.
- 2.Add more Harlequin Rasbora to reach at least 6 individuals, or remove the species.
Species pairing & temperament
- 1.Clear each unsafe species pair by removing or replacing one side — do not stock while red compatibility flags remain.
Suggested swaps
- Single-biome community: e.g. soft-water South Americans together (tetras + corydoras + small gourami) — run the pair tool for every add-on.
- Species or centrepiece tank: one main species (or one compatible pair group) in a right-sized aquarium with dither fish from the same water profile — not random continent mixing.
- Where a pleco is the volume problem, consider bristlenose pleco instead of common pleco for sub-200L plans.
Beginner difficulty
advanced
- Serious compatibility or tank-size issues — not a beginner layout until resolved.
Schooling / group size
- Corydoras Catfish is a schooling/shoaling species — keeping only 1 is a serious welfare risk; aim for at least 6.
- Harlequin Rasbora is a schooling/shoaling species — keeping only 1 is a serious welfare risk; aim for at least 6.
Fish behaviour varies. Fishori gives conservative planning guidance based on adult size, temperament, tank size and common aquarium care sources.