Bronze corydoras and Convict cichlid
Can these two share a tank? The assessment below is derived from stored behavioural and environmental traits, not from a compatibility chart.
Can work, but only if the stated conditions are met.
- Minimum volume
- 205 L
- Minimum length
- 130 cm
- Factors considered
- 7
Concerns
Convict cichlid becomes markedly more aggressive while spawning. A pairing that has been peaceful for months can change within a day, so plan for where the other animal goes if it does.
Derived from: traits.breedingAggression
Convict cichlid defends a territory and both animals use the same part of the tank, so give the territory-holder a defensible area away from the main swimming space.
Derived from: traits.territoriality and zone on both records
Both species occupy the bottom of the tank, so allow for the shared space when judging the footprint.
Derived from: zone and traits.activity on both records
Why it can work
- Temperature requirements overlap comfortably at 22–26 °C, with room for both animals to sit inside their preferred range.
- pH requirements overlap at 6.5–7.8.
- Hardness requirements overlap at 6–18 °dGH.
- Bronze corydoras needs a group of at least 6. Kept in smaller numbers it is not simply lonely — shoaling species held below their threshold show chronic stress behaviour, colour loss and, in several species, increased aggression towards tankmates.
Conditions
Most interesting pairings are conditional on something. These are the things the keeper can actually change.
- At least 6 Bronze corydoras, counted as one group
- At least 205 L with a footprint of 130 cm or more, before counting anything else in the tank
Derived, or documented?
These are different claims and are shown separately. The verdict above is derived from stored traits — arithmetic on AquariumHQ's own records. Whether the pairing is actually reported to work is a separate question, and for most pairs the honest answer is that we hold nothing.
Environmental compatibility
Derived from stored traits
Temperature, pH, hardness, size and behavioural traits compared between the two records. Sound as far as it goes, and it is not evidence that the pairing works.
Behavioural evidence
Widely reported in practice
Reported consistently across aquarium practice without a single citable source. Treated as real but not as measurement.
AquariumHQ's overall position
Workable while the convicts are immature and unreliable once they are not. A pair that spawns will claim the substrate, and corydoras have nowhere else to go.
What would change it: Keeping convicts that do not pair, or a tank long enough that a defended territory leaves genuine refuge elsewhere. Neither is something a keeper can guarantee in advance.
Factor by factor
- Environmental overlapDerived
Both tolerate ordinary community water and the ranges overlap without difficulty. Water is not the problem here, which is exactly why this pairing gets recommended.
- Breeding aggressionReported
A convict pair that spawns changes the tank completely. Reports are consistent that a breeding pair will hold and defend a territory covering most of a small aquarium, and drive off anything entering it — including bottom-dwellers that have no interest in the eggs. The aggression is not a temperament flaw; it is normal parental behaviour in a fish that breeds readily and often.
- Bottom-zone conflictDerived
Convicts spawn on and defend the substrate, which is where corydoras live. The two occupy the same zone at exactly the moment one of them becomes intolerant of company.
- Behaviour outside breedingReported
Juvenile and non-breeding convicts are frequently unremarkable tankmates, which is what makes this pairing deceptive: it works until it suddenly does not, and the change is triggered by the fish maturing rather than by anything the keeper did.
| Depends on | How much |
|---|---|
| Tank size and dimensions | decisive |
| Life stage | decisive |
| The individual animal | significant |
How good is the overlap?
Whether two ranges intersect is a necessary condition, not evidence. What matters is WHERE the shared band sits: an overlap at the top of one animal's range and the bottom of the other's is a forced compromise however wide it looks, and it is the case a simple intersection test cannot see.
| Dimension | Assessment | What that means here |
|---|---|---|
| Temperature | Comfortable for both | The shared band 22–26 °C sits centrally in both ranges, with room to drift. |
| pH | Comfortable for both | The shared band 6.5–7.8 pH sits centrally in both ranges, with room to drift. |
| Hardness | Comfortable for both | The shared band 6–18 °dGH sits centrally in both ranges, with room to drift. |
Factor by factor
Every factor states what it rests on. Most are derived from the traits stored on both records — sound arithmetic on AquariumHQ's own data, and not a report about how the pairing actually goes. Where a factor says 'not known', the data is missing and saying so matters, because a missing factor and a favourable one look identical once both are absent.
| Factor | Basis | Finding |
|---|---|---|
| Temperature | Derived from stored traits | Comfortable for both. The shared band 22–26 °C sits centrally in both ranges, with room to drift. |
| pH | Derived from stored traits | Comfortable for both. The shared band 6.5–7.8 pH sits centrally in both ranges, with room to drift. |
| Hardness | Derived from stored traits | Comfortable for both. The shared band 6–18 °dGH sits centrally in both ranges, with room to drift. |
| Body size | Derived from stored traits | Convict cichlid reaches about 15 cm against 7 cm for Bronze corydoras — a ratio of 2.1. Size disparity drives opportunistic predation independently of temperament. |
| Predation | Derived from stored traits | Highest predation risk in either direction is "high". |
| Territoriality | Derived from stored traits | Strongest territoriality across the pair is "strong". |
| Breeding aggression | Evidence-backed | Breeding aggression reaches "strong". A pairing peaceful for months can change within a day of a spawn. Reported: A convict pair that spawns changes the tank completely. Reports are consistent that a breeding pair will hold and defend a territory covering most of a small aquarium, and drive off anything entering it — including bottom-dwellers that have no interest in the eggs. The aggression is not a temperament flaw; it is normal parental behaviour in a fish that breeds readily and often. |
| Fin-nipping | Derived from stored traits | No nipper-and-target combination between these two. |
| Aggression | Evidence-backed | Strongest intraspecific aggression across the pair is "strong". It bears on the pairing because a fish under pressure from its own kind redirects. Reported: A convict pair that spawns changes the tank completely. Reports are consistent that a breeding pair will hold and defend a territory covering most of a small aquarium, and drive off anything entering it — including bottom-dwellers that have no interest in the eggs. The aggression is not a temperament flaw; it is normal parental behaviour in a fish that breeds readily and often. |
| Social requirements | Derived from stored traits | Bronze corydoras needs at least 6. A shoaling species held below its threshold shows chronic stress and, in several species, increased aggression towards tankmates. |
| Group-size dependency | Derived from stored traits | The outcome depends on group size as much as on the pairing: under-grouped shoalers nip more and hide more. |
| Tank zone | Derived from stored traits | Both occupy the bottom of the tank, so the shared space is under pressure. |
| Activity level | Derived from stored traits | Activity levels are compatible. |
| Food competition | Derived from stored traits | Both are omnivores feeding in the same part of the tank. |
| Risk to shrimp and snails | Derived from stored traits | Highest risk either animal poses to dwarf shrimp or snails is "near-certain". |
| Effect on plants | Derived from stored traits | Convict cichlid uproots plants, which constrains the aquascape rather than the pairing. |
| Tank dimensions | Derived from stored traits | The more demanding of the two needs at least 150 L and 100 cm of length before anything else is in the tank. Volume alone does not describe a home for a fish that swims in straight lines. |
| Life stage | Evidence-backed | Life-stage dependency: decisive. See the documented record. |
| Individual variation | Evidence-backed | Individual variation: significant. |
Environmental overlap
| Parameter | Shared range | Reading |
|---|---|---|
| Temperature | 22–26 °C | Aim for the middle of the shared band. |
| pH | 6.5–7.8 | Stability matters more than the exact figure. |
| Hardness | 6–18 °dGH | Check your source water before committing. |
What this assessment cannot tell you
- Individual temperament varies, particularly in cichlids and in bettas, and can override a favourable verdict for Bronze corydoras or Convict cichlid.
- The assessment is for the pair in isolation. A third species can change the outcome in either direction.
- Both animals are assessed at adult size, not at the size they are sold.
- A verdict is a statement about probability, not a guarantee.