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PubMed2026

Body tactile stimulation intensifies appeasement behavior in a cichlid fish.

Social touch, provided by body tactile stimulation (TS), is known to trigger appeasement behavior and social stability in mammals. Recent studies have shown that TS also plays a role in regulating social interactions in fish by reducing aggression between individuals. While this effect may stem from decreased aggression in dominants, the potential contribution of increased appeasement behavior in subordinates has been overlooked. Here, we investigated whether TS facilitates the onset of appeasement behavior in the cichlid fish Geophagus iporangensis, a species that exhibits clear dominance-subordination relationships. Isolated individuals were assigned to one of two treatments, either with TS (provided by plastic sticks lined with silicone bristles) or without it for 21 days. Then, each fish was paired with a socially experienced dominant individual to enable rapid hierarchy resolution. Initial appeasement scores did not differ between treatments. However, individuals who experienced TS exhibited significantly higher appeasement scores during the final 5 min of the contest than the control group. Additionally, fish under TS showed an increase in the appeasement score after 10 min of agonistic interaction, while it did not change in the treatment without TS. Overall, this study provides the first evidence that TS can mitigate aggressive interactions by intensifying subordinates' appeasement behavior, thereby affecting social dynamics similarly to mammals.

aggression↗
PubMed1978

Residues of organochlorine insecticides and polychlorinated biphenyls in fish from Lakes Huron and Superior, Canada--1968-76.

Five species of fish from Lake Superior and 12 species from Lake Huron were analyzed for organochlorine pesticides and polychlorinated biphenyls (PCBs) between 1968 and 1975. Mean residues of sigma DDT peaked at 1.72 ppm and 7.60 ppm in lake trout (Salvelinus namaycush) from Lakes Superior and Huron, respectively. By 1975, the mean level of sigma DDT had decreased in lake trout and was highest in bloaters (Coregonus hoi) from both lakes: 1.06 ppm and 1.87 ppm, respectively. Dieldrin levels in fish from Lake Superior changed little over the same period. However, in 1969-70, dieldrin levels in fish from Lake Huron exceeded the 0.3 ppm tolerance level set by Health and Welfare Canada or the Food and Drug Administration, U.S. Department of Health, Education, and Welfare in 5 percent of lake whitefish (Coregonus clupeaformis) and 10 percent of bloaters. By 1975, 50 percent of bloaters caught in Georgian Bay and North Channel had dieldrin levels above 0.3 ppm. PCB residues declined in lake trout and lake whitefish caught in Lake Superior between 1971 and 1975, but increased slightly in bloaters and white sucker (Catostomus commersoni). Mean PCB residues in bloaters caught in Lake Huron in 1969-71 and 1975-76, and splake (Salvelinus fontinalis and S. namaycush) and cisco (Coregonus artedii) caught in 1975 exceeded the 2 ppm tolerance level.

Animals↗
PubMed1976

The influence on breeding, production, and acid-base balance when mink are fed on acidified feed.

It has been shown, partly in an investigation in which female mink were subject to increasing quantities of acid in their feed, and partly in an investigation of experimental animals which were fed with various concentrations of acid-preserved fishsilage, that there is a marked risk for a change of the acid-base balance to a metabolic acidosis when pH in the feed comes lower than 5. These investigations are also considered to show that mink's reproductive ability and general welfare is considerably affected when fed with large quantities of acid-preserved fish feed over a longer period, possibly because of alterations in the acid base balance. It is possible to reduce or avoid metabolic acidosis in mink by neutralizing silage or feed.

Acid-Base Imbalance↗
PubMed1979

Mercury, arsenic, and cadmium in fish, water, and sediment of American Falls Reservoir, Idaho, 1974.

Mercury and cadmium were found in fish, water, and sediment of American Falls Reservoir (AFR), Idaho. Mercury and cadmium levels in some fish exceeded human health standards set by the Food and Drug Administration, U.S. Department of Health, Education and Welfare, and the World Health Organization. Analyses performed on the flesh of rainbow trout showed mercury residues of up to 1.20 mg/kg, which were higher than residues previously reported in trout collected in 1970 and 1971 from AFR. Cadmium residue levels were as high as 0.80 mg/kg. Although arsenic was found in reservoir sediment at levels of 1.36-2.40 mg/kg, it was not detected in fish.

Animals↗
PubMed1977

PCB's in fish from selected waters of New York State.

PCB residues in fish from 41 stations throughout New York State were monitored in 1975. Nearly all fish contained PCB's in detectable amounts although the levels of contamination and specific Aroclor varied. The Hudson River contained the highest known PCB concentrations within the United States; levels often exceeded 100 ppm. Other waters and fish which were significantly contaminated include Lake Ontario salmonids and Cayuga Lake lake trout. Onondaga Lake, previously closed to fishing because of mercury contamination, also appears to have abnormally high levels of PCB's approaching in some instances the action level of the Food and Drug Administration, U.S. Department of Health, Education, and Welfare. Samples from marine waters generally have contaminant levels substantially below 5.0 ppm.

Animals↗
PubMed1979

Polychlorinated biphenyls and other organic chemical residues in fish from major watersheds of the United States, 1976.

Composite samples of fish were collected from major United States watersheds in 1976 and analyzed for PCBs and related organic chemicals. PCBs were found in 93 percent of the fish samples; 53 percent of the samples contained more than 5 ppm PCBs, whole fish basis, which is the current tolerance level set by the Food and Drug Administration, U.S. Department of Health, Education and Welfare. Only 14 percent of the samples contained less than the proposed action level of 2 ppm PCBs. PCB concentrations ranged from less than 0.3 ppm to 140 ppm in the composite samples. sigma DDT concentrations ranged from less than 0.05 ppm to 4.53 ppm. Hexachlorobenzene was identified in 19 percent of the samples, and chlordane components were identified in 36 percent of the samples. Chemicals identified by gas chromatography/mass spectrometry but not quantified include chlorinated benzenes, styrenes, anisoles, phenols, anilines, propanes, and butadienes, as well as mixtures of petroleum hydrocarbons.

Animals↗
PubMed1978

Residues of organochlorine insecticides and polychlorinated biphenyls in fish from Lakes Saint Clair and Erie, Canada--1968-76.

Eighteen species of fish from Lake Saint Clair and 19 species from Lake Erie were analyzed for organochlorine pesticides and polychlorinated biphenyls (PCBs) between 1968 and 1976. Mean residues of sigma DDT peaked at 1.19 ppm in longnose gar (Lepisosteus osseus) caught in Lake Saint Clair in 1970-71, but had declined in all species by 1975-76. Dieldrin levels in fish tissues increased over the same period. White bass (Morone chrysops), caught in 1975 in Lake Erie, had the highest mean residue of dieldrin at 0.17 ppm. PCB residues increased in some species and decreased in others. PCB residues exceeding the tolerance level of Health and Welfare Canada were found in the following: from Lake Saint Clair, smallmouth bass (Micropterus dolomieui) in 1975 and channel catfish (Ictalurus punctatus) in 1971; from Lake Erie, coho salmon (Oncorhynchus kisutch) in 1970, smallmouth bass, alewife (Alosa pseudoharengus), freshwater drum (Aplodinotus grunniens), and gizzard shad (Dorosoma cepedianum) in 1971, and white bass in 1971 and 1976.

Animals↗