Flycaster made a good point here - livewell/bait tank hypothermia. Ice is cheap, convenient and will induce hypothermia in livewell water, increase DO concentration a little (Henry’s Law) and reduce fish metabolism and physiological oxygen demand during transport and captivity. Ice is much cheaper than a refrigeration unit, batteries, upkeep, repair, etc.

My buddy, a fish hatchery biologist shared this information with me last week about water temperature stress when transporting live minnows/shad.

Temperature shock stress is a secondary stressor for all live bait fishermen, especially in the summer and hot environmental waters. Minnows/shad experience extremely high stresses when captured (netted), boxed, handled and transported in hot, harsh summer conditions.

Keep in mind that minnow and shad live fine in their natural summer environmental water every summer in shallow hot lake water – their steady-state environment vs a high stress transport environments in bait tanks and livewells.
The first and most serious water quality stressor negatively affecting live minnow/shad, transport/captivity is hypoxic bait tank/livewell water…. this is acute and chronic livewell suffocation.

Temperature shock is a 2 edged blade that cuts both ways… the temperature stress is less traumatic when bait fish go from warm/hot water to cooler water (iced livewell water).

The temp stress is more serious with many negative side effects when the bait is nettet, handled, hooked up, going from chilled bait tank water to hot summer environmental water.

Reducing transport water temperature in an aerated bait tanks is more comfortable for minnows in the summer when the environmental water is near 80F and higher. Cooler water does hold a little more O2 when aerated and any increase in O2 is better than what Mother Nature provides for bait tank water in the summer.

High stressed minnows/shad being transported do suffocate quickly in the summer when the bait tank is overcrowded.
How much good will chilling summer water do when there is no bait in the bait tank using mechanical aeration? Add live bait and O2 level drops proportional to bait load, more bait consumes more O2.

Aerated bait tank, fresh water, sea level barometric pressure; NO live bait in the bait tank water consuming oxygen:
85 F water – 7.7 PPM DO – O2 Saturation 100% ---- NO bait in the water
80F water – 8.1 PPM DO – O2 Sat 100% ---- NO bait in the water
70F water – 9.0 PPM DO – O2 Sat 100% ---- NO bait in the water
65F water – 9.5 PPM DO – O2 sat 100% ---- NO bait in the water
59F water – 10.2 PPM DO – O2 sat 100% ---- NO bait in the water

Add 1 or 100 live minnows or shad and dissolved O2 is consumed. DO and O2 Sat falls proportionally to increased biomass when additional live baits are added to the bait tank. Add more bait and more O2 is consumed and O2 concentration and saturation drops.


For fish hatcheries, their optimal transport (bait tank/livewell) O2 saturation is continuous 100% DO Saturation whether the transport water contains 5 minnows/shad or 10,000 baits.

The biggest summer bait tank/livewell water quality problem is low oxygen, suffocation is deadly for fish minnows and men and it happens quickly. Chronic suffocation takes a little longer to kill, we see this with lethargic red-nose baits piping, scales sloughing off and baits stacking in the corners of square and rectangle bait tanks and livewells.

Minnows and shad will not stack in square corners of bait tanks and livewells IF the water quality is safe and saturated with dissolved oxygen.

Looking at the big picture of keeping, transporting minnows and shad in the summer, most fishermen are pretty happy with their live bait quality and survival in the summer, ice, chemicals, etc.