Fish can be very sensitive to changes in their environment.  Two types of fish, Colossoma macropomum and Piaractus brachypomus, were put through a temperature test.  This was to see how their bodies reacted to a sudden drop in temperature, followed by a return to normal.  The fish were kept in water that was suddenly cooled from 28. 7°C to 18. 6°C.  This was done for 24 hours.  Then, the water was warmed back up to the original temperature.  The fish were then observed for another 24 hours.

    The fish were carefully monitored.  Blood samples were taken at different times.  This was to track how their bodies were handling the temperature changes.  The times for blood collection were 1 hour after the temperature change, 24 hours after the temperature change, and 24 hours after the temperature was returned to normal.  The good news was that no fish died during the experiment.  This is important because it shows that the fish could handle the temperature changes, at least for a short time.

    One interesting finding was how the fish's blood sugar levels changed.  Colossoma macropomum saw a drop in glucose levels that did not recover even after the temperature was returned to normal.  On the other hand, Piaractus brachypomus experienced an increase in glucose levels just 1 hour after the temperature change.  This shows that the two species react differently to sudden temperature drops.

    Both species showed a decrease in triglycerides levels right after the temperature change.  These levels did not return to normal even after 24 hours of readjustment.  This is important because triglycerides are a type of fat in the blood.  A drop in these levels could affect the fish's energy reserves.

    Cholesterol levels in both species dropped right after the temperature change and 24 hours later.  However, these levels returned to normal after 24 hours of readjustment.  This is interesting because it shows that the fish's bodies can recover from some changes caused by temperature drops.

    The drop in temperature also affected the fish's lactate levels.  Lactate is a substance that builds up in the muscles during intense activity.  Both species saw a reduction in lactate levels right after the temperature change and 24 hours later.  However, only Piaractus brachypomus returned to its initial lactate levels after the temperature was returned to normal.  This suggests that Piaractus brachypomus might be better at handling sudden temperature changes.

    Plasma chloride levels were also affected.  These levels were highest 24 hours after the temperature was returned to normal and lowest right after the temperature change.  This is important because chloride is a type of salt in the blood.  Changes in chloride levels can affect how the fish's bodies work.

    In summary, the sudden drop in temperature followed by a return to normal caused several changes in the fish's bodies.  Piaractus brachypomus seemed to handle these changes better than Colossoma macropomum.  This is interesting because it shows that different species of fish can react differently to the same environmental changes.  This information can be useful for understanding how fish might react to changes in their natural habitats, such as those caused by climate change.

Fish Blood Changes: How Cold Water Affects Two Tropical Species

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