| Whole Fresh Fish | Intact marine or freshwater fish with skin, fins, eyes and internal features preserved as supplied | Food-quality assessment, morphology checks, market sampling, culinary education and short-term research | Provides the most complete visual representation; allows inspection of body condition, coloration, fins and external damage | Highly perishable; quality declines quickly if temperature control, hygiene and transport time are inadequate | Chilled close to 0–4°C with sanitary handling; should be transported rapidly and protected from physical damage | Freshness indicators, intact anatomy, clear eyes, firm muscle, clean odor, traceable harvest area, delivery time and cold-chain reliability |
| Frozen Whole Fish | Individually frozen or block-frozen whole specimens, commonly used for larger fish and reference samples | Long-distance trade, reference collections, product verification, teaching and research where immediate examination is not required | Longer usable life than fresh specimens; suitable for international transport when continuously frozen | Freezing can alter texture and may cause ice-crystal damage, dehydration or freezer burn if poorly packed or repeatedly thawed | Generally maintained at −18°C or colder during storage and transport, subject to the buyer’s protocol and applicable regulations | Core temperature, packaging integrity, absence of thaw-refreeze evidence, glazing or moisture control, species identity and shipment documentation |
| Dried or Taxidermied Whole Fish | Air-dried, professionally mounted or articulated whole fish for display and reference | Museums, educational institutions, interior displays, cultural collections and non-destructive visual teaching | Stable at room temperature when properly prepared; visually attractive and easy to display without refrigeration | Can become brittle, fade or attract pests; internal anatomy and genetic material are usually not suitable for detailed analysis | Kept dry, clean and protected from direct sunlight, excessive humidity, pests and handling pressure | Accurate species identification, natural proportions, stable mounting, low odor, absence of insect damage, labeling and legal acquisition records |
| Formalin-Preserved Whole Fish | Small or medium fish fixed in buffered formalin for morphology and anatomical reference | Taxonomy, comparative anatomy, biodiversity studies, museum collections and classroom demonstrations | Maintains overall body form and many external anatomical characteristics for long-term reference | Formalin is hazardous; it can damage nucleic acids and requires regulated handling, labeling, ventilation and disposal | Fixed according to an approved laboratory protocol and commonly transferred to an appropriate long-term storage medium after fixation | Correct fixation, specimen-to-fixative ratio, label durability, container seal, safety documentation, species identity and import restrictions |
| Ethanol-Preserved Whole Fish | Small fish or larval specimens stored in laboratory-grade ethanol at a concentration selected for the intended analysis | Genetic studies, taxonomic research, biodiversity surveys and teaching collections | More compatible with many DNA-based applications than formalin-fixed material when collected and stored correctly | Ethanol is flammable; it may cause tissue shrinkage, color loss and evaporation if containers are not properly sealed | Stored in sealed, chemically compatible containers; ethanol concentration and replacement schedule should follow the research protocol | DNA suitability, correct preservative concentration, leak-proof packaging, remaining liquid volume, specimen completeness and chain of custody |
| Fish Tissue Samples | Muscle, liver, gill, fin clip or other defined tissue portions collected from identified fish | Genetic testing, contaminant analysis, nutritional studies, disease screening and population research | Efficient to transport and analyze; requires less storage space than whole specimens | Provides limited information about external morphology, age structure and whole-body condition | Often frozen or preserved using a validated molecular or analytical protocol; temperature requirements vary by test | Correct tissue type, sample mass, contamination control, collection date, species and location records, preservative compatibility and temperature history |
| Fin Clips and Small External Tissue Samples | Clips from caudal, dorsal or pectoral fins collected with minimally invasive methods | Population genetics, species identification, conservation monitoring and aquaculture broodstock screening | Small, lightweight and relatively simple to collect; may reduce the need to sacrifice the fish | May provide insufficient material for some analyses; contamination or incorrect labeling can compromise results | Stored dry, frozen or in a validated preservative according to the downstream molecular method | Sample size, DNA integrity, non-cross-contamination, unique identification code, collection permit and reliable metadata |
| Scales | Individual scales or scale sets from species in which scales are suitable for age or growth assessment | Age estimation, growth analysis, environmental reconstruction and fisheries research | Lightweight, inexpensive and generally easy to archive; collection can be less destructive than collecting whole fish | Scales can be lost, regenerated or difficult to interpret in some species; sampling location affects comparability | Usually cleaned, dried and stored in labeled envelopes or containers under dry conditions | Species, body location, number of scales, cleanliness, absence of breakage, sampling date and standardized collection method |
| Otoliths | Pair of calcium-carbonate ear stones, including sagittae from many bony fish species | Age determination, stock identification, migration studies, food-web research and chemical analysis | Durable and information-rich; growth rings and chemical composition can support long-term fisheries research | Must be removed carefully; small otoliths can be difficult to handle and preparation may require specialized equipment | Cleaned and dried in labeled containers; storage should prevent mixing, abrasion and chemical contamination | Correct species and side, intact structure, verified fish length and capture data, contamination-free preparation and traceable labeling |
| Fish Skeletons | Disarticulated or articulated skeletal preparations from whole fish | Comparative anatomy, vertebrate morphology, education, museum reference and biomechanics | Reveals internal structure and skeletal relationships that are not visible in intact specimens | Fragile; preparation can remove soft-tissue information and incorrect cleaning may damage small bones | Kept dry and protected from dust, pests, humidity, crushing and excessive ultraviolet exposure | Completeness, anatomical accuracy, clean preparation, correct assembly, stable support, species identification and documentation |
| Fish Eggs and Larvae | Fertilized eggs, embryos, larvae or early juvenile stages collected for developmental studies | Hatchery research, reproductive biology, larval identification, ecology and fisheries recruitment surveys | Useful for studying development, spawning timing and early-life survival | Very delicate and difficult to identify visually; viability and condition can change rapidly after collection | Live or preserved according to the study design, with strict control of temperature, oxygen, water quality or fixative conditions | Developmental stage, viability, collection time, water conditions, species confirmation, handling duration and transport conditions |
| Parasites and Associated Organisms | Fish parasites, commensals or other organisms recovered from skin, gills, gut or internal organs | Veterinary science, aquatic disease surveillance, host–parasite studies and ecosystem research | Supports health assessment and ecological analysis; can reveal relationships between fish, environment and pathogens | Small organisms can be damaged or lost during collection; identification often requires microscopy or molecular testing | Preserved using a method appropriate to morphology or genetic analysis, with separate labeling for host and parasite | Exact host identity, collection site on the fish, specimen condition, preservative suitability, biosecurity controls and complete metadata |
