Indian threadfin (Alectis indicus) care guide

Group
Marine fish
Other names
Diamond trevally, Mirror fish, Plumed trevally
Family
Carangidae (jacks and trevallies)
Origin
Tropical Indo-West Pacific, from East Africa and the Red Sea to India, Japan, Indonesia and northern Australia; coastal reefs at 20–100 m.
Water
saltwater
Maximum size
165 cm
Temperature
24–27°C
pH
8.1–8.4
Hardness
Salinity SG 1.020–1.025
Care level
expert
Temperament
semi_aggressive
Reef safe
no

Care

Juveniles, with long trailing fin filaments thought to mimic jellyfish, are moderately popular, but adults reach 165 cm and 25 kg. This fish is for public-aquarium-sized systems: it outgrows home aquaria and needs a very large volume of open swimming space, so no home tank size is given. Water figures given here are general marine aquarium guidance, not species-specific: 24–27 °C, pH 8.1–8.4 and salinity SG 1.020–1.025 (fish-only systems). Juveniles use estuaries and seagrass and need peaceful tankmates while small, as their fin filaments are easily nipped. Selling: our policies require the adult size and long-term tank needs to be stated clearly in the listing. Large fish must travel by a specialist live-animal courier (see the Livestock shipping guide). Sources: Wikipedia, List of marine aquarium fish species (en.wikipedia.org/wiki/Listofmarineaquariumfishspecies); Wikipedia (en.wikipedia.org/wiki/Alectisindicus). Checked October 2026.

Diet

A predator of fish, squid and other cephalopods, jellyfish and crustaceans. Feed chopped fish, squid, prawn and krill.

Breeding

Little known. In Indonesia pairs have been seen spawning by day over a deep shoal between tides. Not bred in captivity.

Compatibility and tank mates

Not reef safe. Keep juveniles with peaceful fish that will not nip their trailing fins; adults eat any fish they can swallow.

Last updated 8 October 2026. Community-edited care guide on Aquatic-Auctions.

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