Thirty gallons, and respect for what happens next
The minimum tank for convict cichlids is 30 gallons for one fish or a pair, stepping up toward 40 gallons or more if the pair shares with other fish. Convicts stay fairly compact — males reach a moderate size, females smaller — but tank size for this species is not really about the fish's length. It is about territory. A convict claims a cave and the ground around it, and a breeding pair, which convicts become with almost no encouragement, defends a much larger zone with total commitment, herding fry and driving off fish many times their size.
In 30 gallons with rockwork dividing the space, a pair can hold one end while other fish live at the other. In a small tank there is no other end, and the tankmates live under siege.
Furnishing a tank convicts will rearrange
Build the convict tank around defensible structure: caves, rock piles, clay pots or similar shelters offering a cave with one entrance, and a substrate they can dig — because they will dig. Convicts excavate pits, move gravel, and uproot plants as part of nesting behaviour, so anchor rocks securely on the glass rather than on top of substrate the fish will undermine, keep plants robust, potted, or floating, and accept the landscaping as partly theirs. Break the tank into visual zones with rockwork and wood so a chased fish can get out of sight; a bare tank gives the dominant convict a clear view of everyone it objects to, which is exactly what you do not want.
Stable, clean water and regular maintenance complete the setup — convicts are notably hardy, but hardiness used as an excuse for neglect shows up in ragged fins and constant aggression.
The breeding question, answered honestly
Anyone keeping a male and female convict should plan for fry, because this species breeds readily, guards eggs laid on a cave ceiling or flat rock, and raises free-swimming babies in a guarded parade around the tank. It is wonderful to watch and genuinely demanding: the parents' defence peaks exactly when the fry appear, other fish need the space this article keeps emphasising, and the young fish will need homes. If you do not want breeding, keep a single convict — they make personable, interactive solo fish — or a single-sex group in a suitably large tank. Do not rely on tankmates eating the fry as a population plan; convict parents are too good at their job.
Tankmates that can hold their own
Companions for convicts must be robust, fast, and able to use space away from the convicts' cave: similarly tough fish of comparable size in a large tank, or sturdy dither fish that stay mid-water. Delicate, slow, long-finned, or timid fish do not belong in a convict tank, and bottom fish that blunder into the breeding cave will be treated as invaders. A single convict, by contrast, fits more community setups than its reputation suggests, provided tankmates are not small enough to be eaten or fragile enough to be bullied. Judge the individual fish in front of you — convict temperaments vary — but furnish and stock for the territorial version, not the hopeful one.
A tank the whole household reads the same way
Convict tanks suffer most from well-meant surprises: a new fish added during a fry-guarding week, a cave moved during cleaning, a feeding change nobody recorded. KinsLe Family Sharing lets everyone who helps with your convict cichlids see the same profile and care details, so the pair's breeding status, territory layout, and feeding routine stay common knowledge in the house.