| Laberdan |
| labial |
| labial fold |
| labial furrows |
| Labrador cure |
| Labrador Sea |
| Labrisomids |
| labyrinth |
| labyrinth organ |
| Laccadive Sea |
| lachrymal |
| lachrymal groove |
| Lachsbückling |
| Lachshering |
| laciniate |
| lacustrian |
| lacustrine |
| Lady day fish |
| lagena |
| Laggy |
| lagoon area |
| lagoon floor |
| lagoon fringing reef area |
| Lakérda |
| lam net |
| Lamayo |
| lamellae |
| laminar flow |
| Laminarin |
| Lamnoid |
| lampara |
| Lampreys |
| lanceolate |
| Lancetfishes |
| land-locked |
| landings |
| landrace |
| landscape diversity |
| lantern net |
| Lanternbellies |
| Lanterneye fishes |
| Lanternfishes |
| Lap tail |
| lapillus |
| lappet |
| lapsus calami |
| Laptev Sea (or Nordenskjöld Sea) |
| Large-tooth flounders |
| Largenose fishes |
| Larsen midwater trawl |
| larva |
| larvaceans |
| larvae |
| larval development |
| larval settlement |
| LarvalBase |
| larviparous |
| larvivore |
| larvophile |
| late embryo |
| lateral |
| lateral canal |
| lateral clasper fold |
| lateral ethmoids |
| lateral keel |
| lateral line |
| lateral line count |
| lateral line scales |
| lateral scale rows |
| lateral series scales |
| lateral skin fold |
| Lateralis system |
| laterocaudal |
| laterosensory pores |
| latitude |
| Laukkasvolattu savustettu silli |
| Laverbread |
| Law of Fishing |
| lay on back |
| lay parallel on substrate |
| layer depth effect |
| layer packed |
| LD50 |
| lead line |
| Leaffishes |
| lecithotrophic larva |
| lecithotrophic live bearer |
| lecithotrophy |
| lecitrophic |
| lectotype |
| lee |
| leeward |
| Lee´s phenomenon |
| Lefteye flounders |
| Leggy |
| Lek |
| length at first maturity |
| length distribution |
| Length of caudal peduncle |
| length-weight relationship |
| lentic |
| lepidophagous |
| lepidophagy |
| lepidorthosis |
| lepidotrichia |
| leptocephalus |
| leptocercal |
| Leptochilichthyids |
| Lessepsian migration |
| lethargy |
| leucophore |
| levant |
| levee |
| lever net |
| life cycle |
| life table |
| lifespan |
| lift net |
| Lightfishes |
| Ligurian Sea |
| liman |
| limicolous |
| liming |
| limit reference point |
| limited entry fishery |
| limnicolous |
| limnion |
| limnivorous |
| limnodromous |
| limnology |
| Lincoln Sea |
| Lindsey´s rule |
| lineage |
| linear |
| liner |
| Linf |
| Linnaean tautonymy |
| lip groove |
| lipid |
| lipophore |
| lipostichaerin |
| lips |
| liquamen |
| liquid fish |
| listserver |
| lithophilic |
| litter |
| litter size |
| littoral |
| live weight |
| live well |
| live-bearing |
| Livebearers |
| Lizardfishes |
| Lm |
| Loach catfishes |
| Loach gobies |
| Loaches |
| lobate |
| lobe |
| Local Area Network |
| local extinction |
| locking mechanism |
| Locks |
| locus |
| logical database |
| logistic population growth |
| loin |
| London cut cure |
| Long-finned pike |
| long-term potential yield |
| Long-whiskered catfishes |
| longevity |
| longitude |
| longitudinal |
| longitudinal scale series |
| longline |
| longliner |
| Longneck eels |
| Longnose chimaeras |
| Longtail catfishes |
| Loosejaws |
| Lophichthyid frogfishes |
| lophocercal |
| Lorenzini´s ampullae |
| Los Angeles County Museum of Natural History, Los Angeles |
| lotic |
| Louisiana State University, Division of Fishes, Museum of Zoology, Baton Rouge |
| Louisiana Tech University, Ruston, Louisiana |
| Louisiana Wildlife and Fisheries, Marine Biological Laboratory Museum, Louisiana |
| Louvars |
| low island earthform |
| lower limb |
| Loweye catfishes |
| lozenge-shaped |
| Lt |
| luciferase |
| luciferin |
| luciferous |
| lumbar |
| lumen |
| luminous organ |
| Lumpfishes and snailfishes |
| lumping |
| lunar rhythm |
| lunate |
| lunker |
| lunula |
| lure |
| Lutefisk |
| Lycophyta |
| lymphatic heart |
